Linux Programmer's Manual PROC(5)

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PROC(5)                   Linux Programmer's Manual                  PROC(5)

NAME         top

       proc - process information pseudo-filesystem

DESCRIPTION         top

       The proc filesystem is a pseudo-filesystem which provides an       interface to kernel data structures.  It is commonly mounted at       /proc.  Most of it is read-only, but some files allow kernel       variables to be changed.       The following list describes many of the files and directories under       the /proc hierarchy.       /proc/[pid]              There is a numerical subdirectory for each running process;              the subdirectory is named by the process ID.  Each such              subdirectory contains the following pseudo-files and              directories.       /proc/[pid]/attr              The files in this directory provide an API for security              modules.  The contents of this directory are files that can be              read and written in order to set security-related attributes.              This directory was added to support SELinux, but the intention              was that the API be general enough to support other security              modules.  For the purpose of explanation, examples of how              SELinux uses these files are provided below.              This directory is present only if the kernel was configured              with CONFIG_SECURITY.       /proc/[pid]/attr/current (since Linux 2.6.0)              The contents of this file represent the current security              attributes of the process.              In SELinux, this file is used to get the security context of a              process.  Prior to Linux 2.6.11, this file could not be used              to set the security context (a write was always denied), since              SELinux limited process security transitions to execve(2) (see              the description of /proc/[pid]/attr/exec, below).  Since Linux              2.6.11, SELinux lifted this restriction and began supporting              "set" operations via writes to this node if authorized by              policy, although use of this operation is only suitable for              applications that are trusted to maintain any desired              separation between the old and new security contexts.  Prior              to Linux 2.6.28, SELinux did not allow threads within a multi-              threaded process to set their security context via this node              as it would yield an inconsistency among the security contexts              of the threads sharing the same memory space.  Since Linux              2.6.28, SELinux lifted this restriction and began supporting              "set" operations for threads within a multithreaded process if              the new security context is bounded by the old security              context, where the bounded relation is defined in policy and              guarantees that the new security context has a subset of the              permissions of the old security context.  Other security              modules may choose to support "set" operations via writes to              this node.       /proc/[pid]/attr/exec (since Linux 2.6.0)              This file represents the attributes to assign to the process              upon a subsequent execve(2).              In SELinux, this is needed to support role/domain transitions,              and execve(2) is the preferred point to make such transitions              because it offers better control over the initialization of              the process in the new security label and the inheritance of              state.  In SELinux, this attribute is reset on execve(2) so              that the new program reverts to the default behavior for any              execve(2) calls that it may make.  In SELinux, a process can              set only its own /proc/[pid]/attr/exec attribute.       /proc/[pid]/attr/fscreate (since Linux 2.6.0)              This file represents the attributes to assign to files created              by subsequent calls to open(2), mkdir(2), symlink(2), and              mknod(2)              SELinux employs this file to support creation of a file (using              the aforementioned system calls) in a secure state, so that              there is no risk of inappropriate access being obtained              between the time of creation and the time that attributes are              set.  In SELinux, this attribute is reset on execve(2), so              that the new program reverts to the default behavior for any              file creation calls it may make, but the attribute will              persist across multiple file creation calls within a program              unless it is explicitly reset.  In SELinux, a process can set              only its own /proc/[pid]/attr/fscreate attribute.       /proc/[pid]/attr/prev (since Linux 2.6.0)              This file contains the security context of the process before              the last execve(2); that is, the previous value of              /proc/[pid]/attr/current.       /proc/[pid]/attr/keycreate (since Linux 2.6.18)              If a process writes a security context into this file, all              subsequently created keys (add_key(2)) will be labeled with              this context.  For further information, see the kernel source              file Documentation/keys.txt.       /proc/[pid]/attr/socketcreate (since Linux 2.6.18)              If a process writes a security context into this file, all              subsequently created sockets will be labeled with this              context.       /proc/[pid]/auxv (since 2.6.0-test7)              This contains the contents of the ELF interpreter information              passed to the process at exec time.  The format is one              unsigned long ID plus one unsigned long value for each entry.              The last entry contains two zeros.  See also getauxval(3).       /proc/[pid]/cgroup (since Linux 2.6.24)              This file describes control groups to which the process/task              belongs.  For each cgroup hierarchy there is one entry              containing colon-separated fields of the form:                  5:cpuacct,cpu,cpuset:/daemons              The colon-separated fields are, from left to right:                  1. hierarchy ID number                  2. set of subsystems bound to the hierarchy                  3. control group in the hierarchy to which the process                     belongs              This file is present only if the CONFIG_CGROUPS kernel              configuration option is enabled.       /proc/[pid]/clear_refs (since Linux 2.6.22)              This is a write-only file, writable only by owner of the              process.              The following values may be written to the file:              1 (since Linux 2.6.22)                     Reset the PG_Referenced and ACCESSED/YOUNG bits for all                     the pages associated with the process.  (Before kernel                     2.6.32, writing any nonzero value to this file had this                     effect.)              2 (since Linux 2.6.32)                     Reset the PG_Referenced and ACCESSED/YOUNG bits for all                     anonymous pages associated with the process.              3 (since Linux 2.6.32)                     Reset the PG_Referenced and ACCESSED/YOUNG bits for all                     file-mapped pages associated with the process.              Clearing the PG_Referenced and ACCESSED/YOUNG bits provides a              method to measure approximately how much memory a process is              using.  One first inspects the values in the "Referenced"              fields for the VMAs shown in /proc/[pid]/smaps to get an idea              of the memory footprint of the process.  One then clears the              PG_Referenced and ACCESSED/YOUNG bits and, after some measured              time interval, once again inspects the values in the              "Referenced" fields to get an idea of the change in memory              footprint of the process during the measured interval.  If one              is interested only in inspecting the selected mapping types,              then the value 2 or 3 can be used instead of 1.              A further value can be written to affect a different bit:              4 (since Linux 3.11)                     Clear the soft-dirty bit for all the pages associated                     with the process.  This is used (in conjunction with                     /proc/[pid]/pagemap) by the check-point restore system                     to discover which pages of a process have been dirtied                     since the file /proc/[pid]/clear_refs was written to.              Writing any value to /proc/[pid]/clear_refs other than those              listed above has no effect.              The /proc/[pid]/clear_refs file is present only if the              CONFIG_PROC_PAGE_MONITOR kernel configuration option is              enabled.       /proc/[pid]/cmdline              This read-only file holds the complete command line for the              process, unless the process is a zombie.  In the latter case,              there is nothing in this file: that is, a read on this file              will return 0 characters.  The command-line arguments appear              in this file as a set of strings separated by null bytes              ('\0'), with a further null byte after the last string.       /proc/[pid]/comm (since Linux 2.6.33)              This file exposes the process's comm value—that is, the              command name associated with the process.  Different threads              in the same process may have different comm values, accessible              via /proc/[pid]/task/[tid]/comm.  A thread may modify its comm              value, or that of any of other thread in the same thread group              (see the discussion of CLONE_THREAD in clone(2)), by writing              to the file /proc/self/task/[tid]/comm.  Strings longer than              TASK_COMM_LEN (16) characters are silently truncated.              This file provides a superset of the prctl(2) PR_SET_NAME and              PR_GET_NAME operations, and is employed by              pthread_setname_np(3) when used to rename threads other than              the caller.       /proc/[pid]/coredump_filter (since Linux 2.6.23)              See core(5).       /proc/[pid]/cpuset (since Linux 2.6.12)              See cpuset(7).       /proc/[pid]/cwd              This is a symbolic link to the current working directory of              the process.  To find out the current working directory of              process 20, for instance, you can do this:                  $ cd /proc/20/cwd; /bin/pwd              Note that the pwd command is often a shell built-in, and might              not work properly.  In bash(1), you may use pwd -P.              In a multithreaded process, the contents of this symbolic link              are not available if the main thread has already terminated              (typically by calling pthread_exit(3)).       /proc/[pid]/environ              This file contains the environment for the process.  The              entries are separated by null bytes ('\0'), and there may be a              null byte at the end.  Thus, to print out the environment of              process 1, you would do:                  $ strings /proc/1/environ       /proc/[pid]/exe              Under Linux 2.2 and later, this file is a symbolic link              containing the actual pathname of the executed command.  This              symbolic link can be dereferenced normally; attempting to open              it will open the executable.  You can even type              /proc/[pid]/exe to run another copy of the same executable as              is being run by process [pid].  In a multithreaded process,              the contents of this symbolic link are not available if the              main thread has already terminated (typically by calling              pthread_exit(3)).              Under Linux 2.0 and earlier, /proc/[pid]/exe is a pointer to              the binary which was executed, and appears as a symbolic link.              A readlink(2) call on this file under Linux 2.0 returns a              string in the format:                  [device]:inode              For example, [0301]:1502 would be inode 1502 on device major              03 (IDE, MFM, etc. drives) minor 01 (first partition on the              first drive).              find(1) with the -inum option can be used to locate the file.       /proc/[pid]/fd/              This is a subdirectory containing one entry for each file              which the process has open, named by its file descriptor, and              which is a symbolic link to the actual file.  Thus, 0 is              standard input, 1 standard output, 2 standard error, and so              on.              For file descriptors for pipes and sockets, the entries will              be symbolic links whose content is the file type with the              inode.  A readlink(2) call on this file returns a string in              the format:                  type:[inode]              For example, socket:[2248868] will be a socket and its inode              is 2248868.  For sockets, that inode can be used to find more              information in one of the files under /proc/net/.              For file descriptors that have no corresponding inode (e.g.,              file descriptors produced by epoll_create(2), eventfd(2),              inotify_init(2), signalfd(2), and timerfd(2)), the entry will              be a symbolic link with contents of the form                  anon_inode:<file-type>              In some cases, the file-type is surrounded by square brackets.              For example, an epoll file descriptor will have a symbolic              link whose content is the string anon_inode:[eventpoll].              In a multithreaded process, the contents of this directory are              not available if the main thread has already terminated              (typically by calling pthread_exit(3)).              Programs that will take a filename as a command-line argument,              but will not take input from standard input if no argument is              supplied, or that write to a file named as a command-line              argument, but will not send their output to standard output if              no argument is supplied, can nevertheless be made to use              standard input or standard out using /proc/[pid]/fd.  For              example, assuming that -i is the flag designating an input              file and -o is the flag designating an output file:                  $ foobar -i /proc/self/fd/0 -o /proc/self/fd/1 ...              and you have a working filter.              /proc/self/fd/N is approximately the same as /dev/fd/N in some              UNIX and UNIX-like systems.  Most Linux MAKEDEV scripts              symbolically link /dev/fd to /proc/self/fd, in fact.              Most systems provide symbolic links /dev/stdin, /dev/stdout,              and /dev/stderr, which respectively link to the files 0, 1,              and 2 in /proc/self/fd.  Thus the example command above could              be written as:                  $ foobar -i /dev/stdin -o /dev/stdout ...       /proc/[pid]/fdinfo/ (since Linux 2.6.22)              This is a subdirectory containing one entry for each file              which the process has open, named by its file descriptor.  The              files in this directory are readable only by the owner of the              process.  The contents of each file can be read to obtain              information about the corresponding file descriptor.  The              content depends on the type of file referred to by the              corresponding descriptor.              For regular files and directories, we see something like:                  $ cat /proc/12015/fdinfo/4                  pos:    1000                  flags:  01002002                  mnt_id: 21              The pos field is a decimal number showing the current file              offset.  The flags field is an octal number that displays the              file access mode and file status flags (see open(2)).  The              mnt_id field, present since Linux 3.15, is the ID of the mount              point containing this file.  See the description of              /proc/[pid]/mountinfo.              For eventfd file descriptors (see eventfd(2)), we see the              following fields:                  pos: 0                  flags:    02                  mnt_id:   10                  eventfd-count:               40              eventfd-count is the current value of the eventfd counter, in              hexadecimal.              For epoll file descriptors (see epoll(7)), we see the              following fields:                  pos: 0                  flags:    02                  mnt_id:   10                  tfd:        9 events:       19 data: 74253d2500000009                  tfd:        7 events:       19 data: 74253d2500000007              Each of the lines beginning tfd describes one of the file              descriptors being monitored via the epoll file descriptor (see              epoll_ctl(2) for some details).  The tfd field is the number              of the file descriptor.  The events field is a hexadecimal              mask of the events being monitored for this file descriptor.              The data field is the data value associated with this file              descriptor.              For signalfd file descriptors (see signalfd(2)), we see the              following fields:                  pos: 0                  flags:    02                  mnt_id:   10                  sigmask:  0000000000000006              sigmask is the hexadecimal mask of signals that are accepted              via this signalfd file descriptor.  (In this example, bits 2              and 3 are set, corresponding to the signals SIGINT and              SIGQUIT; see signal(7).)       /proc/[pid]/io (since kernel 2.6.20)              This file contains I/O statistics for the process, for              example:                  # cat /proc/3828/io                  rchar: 323934931                  wchar: 323929600                  syscr: 632687                  syscw: 632675                  read_bytes: 0                  write_bytes: 323932160                  cancelled_write_bytes: 0              The fields are as follows:              rchar: characters read                     The number of bytes which this task has caused to be                     read from storage.  This is simply the sum of bytes                     which this process passed to read(2) and similar system                     calls.  It includes things such as terminal I/O and is                     unaffected by whether or not actual physical disk I/O                     was required (the read might have been satisfied from                     pagecache).              wchar: characters written                     The number of bytes which this task has caused, or                     shall cause to be written to disk.  Similar caveats                     apply here as with rchar.              syscr: read syscalls                     Attempt to count the number of read I/O operations—that                     is, system calls such as read(2) and pread(2).              syscw: write syscalls                     Attempt to count the number of write I/O operations—                     that is, system calls such as write(2) and pwrite(2).              read_bytes: bytes read                     Attempt to count the number of bytes which this process                     really did cause to be fetched from the storage layer.                     This is accurate for block-backed filesystems.              write_bytes: bytes written                     Attempt to count the number of bytes which this process                     caused to be sent to the storage layer.              cancelled_write_bytes:                     The big inaccuracy here is truncate.  If a process                     writes 1MB to a file and then deletes the file, it will                     in fact perform no writeout.  But it will have been                     accounted as having caused 1MB of write.  In other                     words: this field represents the number of bytes which                     this process caused to not happen, by truncating                     pagecache.  A task can cause "negative" I/O too.  If                     this task truncates some dirty pagecache, some I/O                     which another task has been accounted for (in its                     write_bytes) will not be happening.              Note: In the current implementation, things are a bit racy on              32-bit systems: if process A reads process B's /proc/[pid]/io              while process B is updating one of these 64-bit counters,              process A could see an intermediate result.       /proc/[pid]/gid_map (since Linux 3.5)              See user_namespaces(7).       /proc/[pid]/limits (since Linux 2.6.24)              This file displays the soft limit, hard limit, and units of              measurement for each of the process's resource limits (see              getrlimit(2)).  Up to and including Linux 2.6.35, this file is              protected to allow reading only by the real UID of the              process.  Since Linux 2.6.36, this file is readable by all              users on the system.       /proc/[pid]/map_files/ (since kernel 3.3)              This subdirectory contains entries corresponding to memory-              mapped files (see mmap(2)).  Entries are named by memory              region start and end address pair (expressed as hexadecimal              numbers), and are symbolic links to the mapped files              themselves.  Here is an example, with the output wrapped and              reformatted to fit on an 80-column display:                  # ls -l /proc/self/map_files/                  lr--------. 1 root root 64 Apr 16 21:31                              3252e00000-3252e20000 -> /usr/lib64/ld-2.15.so                  ...              Although these entries are present for memory regions that              were mapped with the MAP_FILE flag, the way anonymous shared              memory (regions created with the MAP_ANON | MAP_SHARED flags)              is implemented in Linux means that such regions also appear on              this directory.  Here is an example where the target file is              the deleted /dev/zero one:                  lrw-------. 1 root root 64 Apr 16 21:33                              7fc075d2f000-7fc075e6f000 -> /dev/zero (deleted)              This directory appears only if the CONFIG_CHECKPOINT_RESTORE              kernel configuration option is enabled.  Privilege              (CAP_SYS_ADMIN) is required to view the contents of this              directory.       /proc/[pid]/maps              A file containing the currently mapped memory regions and              their access permissions.  See mmap(2) for some further              information about memory mappings.              The format of the file is:       address           perms offset  dev   inode       pathname       00400000-00452000 r-xp 00000000 08:02 173521      /usr/bin/dbus-daemon       00651000-00652000 r--p 00051000 08:02 173521      /usr/bin/dbus-daemon       00652000-00655000 rw-p 00052000 08:02 173521      /usr/bin/dbus-daemon       00e03000-00e24000 rw-p 00000000 00:00 0           [heap]       00e24000-011f7000 rw-p 00000000 00:00 0           [heap]       ...       35b1800000-35b1820000 r-xp 00000000 08:02 135522  /usr/lib64/ld-2.15.so       35b1a1f000-35b1a20000 r--p 0001f000 08:02 135522  /usr/lib64/ld-2.15.so       35b1a20000-35b1a21000 rw-p 00020000 08:02 135522  /usr/lib64/ld-2.15.so       35b1a21000-35b1a22000 rw-p 00000000 00:00 0       35b1c00000-35b1dac000 r-xp 00000000 08:02 135870  /usr/lib64/libc-2.15.so       35b1dac000-35b1fac000 ---p 001ac000 08:02 135870  /usr/lib64/libc-2.15.so       35b1fac000-35b1fb0000 r--p 001ac000 08:02 135870  /usr/lib64/libc-2.15.so       35b1fb0000-35b1fb2000 rw-p 001b0000 08:02 135870  /usr/lib64/libc-2.15.so       ...       f2c6ff8c000-7f2c7078c000 rw-p 00000000 00:00 0    [stack:986]       ...       7fffb2c0d000-7fffb2c2e000 rw-p 00000000 00:00 0   [stack]       7fffb2d48000-7fffb2d49000 r-xp 00000000 00:00 0   [vdso]              The address field is the address space in the process that the              mapping occupies.  The perms field is a set of permissions:                   r = read                   w = write                   x = execute                   s = shared                   p = private (copy on write)              The offset field is the offset into the file/whatever; dev is              the device (major:minor); inode is the inode on that device.              0 indicates that no inode is associated with the memory              region, as would be the case with BSS (uninitialized data).              The pathname field will usually be the file that is backing              the mapping.  For ELF files, you can easily coordinate with              the offset field by looking at the Offset field in the ELF              program headers (readelf -l).              There are additional helpful pseudo-paths:                   [stack]                          The initial process's (also known as the main                          thread's) stack.                   [stack:<tid>] (since Linux 3.4)                          A thread's stack (where the <tid> is a thread ID).                          It corresponds to the /proc/[pid]/task/[tid]/                          path.                   [vdso] The virtual dynamically linked shared object.                   [heap] The process's heap.              If the pathname field is blank, this is an anonymous mapping              as obtained via the mmap(2) function.  There is no easy way to              coordinate this back to a process's source, short of running              it through gdb(1), strace(1), or similar.              Under Linux 2.0, there is no field giving pathname.       /proc/[pid]/mem              This file can be used to access the pages of a process's              memory through open(2), read(2), and lseek(2).       /proc/[pid]/mountinfo (since Linux 2.6.26)              This file contains information about mount points.  It              contains lines of the form:              36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue              (1)(2)(3)   (4)   (5)      (6)      (7)   (8) (9)   (10)         (11)              The numbers in parentheses are labels for the descriptions              below:              (1)  mount ID: unique identifier of the mount (may be reused                   after umount(2)).              (2)  parent ID: ID of parent mount (or of self for the top of                   the mount tree).              (3)  major:minor: value of st_dev for files on filesystem (see                   stat(2)).              (4)  root: root of the mount within the filesystem.              (5)  mount point: mount point relative to the process's root.              (6)  mount options: per-mount options.              (7)  optional fields: zero or more fields of the form                   "tag[:value]".              (8)  separator: marks the end of the optional fields.              (9)  filesystem type: name of filesystem in the form                   "type[.subtype]".              (10) mount source: filesystem-specific information or "none".              (11) super options: per-superblock options.              Parsers should ignore all unrecognized optional fields.              Currently the possible optional fields are:                   shared:X          mount is shared in peer group X                   master:X          mount is slave to peer group X                   propagate_from:X  mount is slave and receives propagation                                     from peer group X (*)                   unbindable        mount is unbindable              (*) X is the closest dominant peer group under the process's              root.  If X is the immediate master of the mount, or if there              is no dominant peer group under the same root, then only the              "master:X" field is present and not the "propagate_from:X"              field.              For more information on mount propagation see:              Documentation/filesystems/sharedsubtree.txt in the Linux              kernel source tree.       /proc/[pid]/mounts (since Linux 2.4.19)              This is a list of all the filesystems currently mounted in the              process's mount namespace.  The format of this file is              documented in fstab(5).  Since kernel version 2.6.15, this              file is pollable: after opening the file for reading, a change              in this file (i.e., a filesystem mount or unmount) causes              select(2) to mark the file descriptor as readable, and poll(2)              and epoll_wait(2) mark the file as having an error condition.              See namespaces(7) for more information.       /proc/[pid]/mountstats (since Linux 2.6.17)              This file exports information (statistics, configuration              information) about the mount points in the process's mount              namespace.  Lines in this file have the form:              device /dev/sda7 mounted on /home with fstype ext3 [statistics]              (       1      )            ( 2 )             (3 ) (4)              The fields in each line are:              (1)  The name of the mounted device (or "nodevice" if there is                   no corresponding device).              (2)  The mount point within the filesystem tree.              (3)  The filesystem type.              (4)  Optional statistics and configuration information.                   Currently (as at Linux 2.6.26), only NFS filesystems                   export information via this field.              This file is readable only by the owner of the process.              See namespaces(7) for more information.       /proc/[pid]/ns/ (since Linux 3.0)              This is a subdirectory containing one entry for each namespace              that supports being manipulated by setns(2).  For more              information, see namespaces(7).       /proc/[pid]/numa_maps (since Linux 2.6.14)              See numa(7).       /proc/[pid]/oom_adj (since Linux 2.6.11)              This file can be used to adjust the score used to select which              process should be killed in an out-of-memory (OOM) situation.              The kernel uses this value for a bit-shift operation of the              process's oom_score value: valid values are in the range -16              to +15, plus the special value -17, which disables OOM-killing              altogether for this process.  A positive score increases the              likelihood of this process being killed by the OOM-killer; a              negative score decreases the likelihood.              The default value for this file is 0; a new process inherits              its parent's oom_adj setting.  A process must be privileged              (CAP_SYS_RESOURCE) to update this file.              Since Linux 2.6.36, use of this file is deprecated in favor of              /proc/[pid]/oom_score_adj.       /proc/[pid]/oom_score (since Linux 2.6.11)              This file displays the current score that the kernel gives to              this process for the purpose of selecting a process for the              OOM-killer.  A higher score means that the process is more              likely to be selected by the OOM-killer.  The basis for this              score is the amount of memory used by the process, with              increases (+) or decreases (-) for factors including:              * whether the process creates a lot of children using fork(2)                (+);              * whether the process has been running a long time, or has                used a lot of CPU time (-);              * whether the process has a low nice value (i.e., > 0) (+);              * whether the process is privileged (-); and              * whether the process is making direct hardware access (-).              The oom_score also reflects the adjustment specified by the              oom_score_adj or oom_adj setting for the process.       /proc/[pid]/oom_score_adj (since Linux 2.6.36)              This file can be used to adjust the badness heuristic used to              select which process gets killed in out-of-memory conditions.              The badness heuristic assigns a value to each candidate task              ranging from 0 (never kill) to 1000 (always kill) to determine              which process is targeted.  The units are roughly a proportion              along that range of allowed memory the process may allocate              from, based on an estimation of its current memory and swap              use.  For example, if a task is using all allowed memory, its              badness score will be 1000.  If it is using half of its              allowed memory, its score will be 500.              There is an additional factor included in the badness score:              root processes are given 3% extra memory over other tasks.              The amount of "allowed" memory depends on the context in which              the OOM-killer was called.  If it is due to the memory              assigned to the allocating task's cpuset being exhausted, the              allowed memory represents the set of mems assigned to that              cpuset (see cpuset(7)).  If it is due to a mempolicy's node(s)              being exhausted, the allowed memory represents the set of              mempolicy nodes.  If it is due to a memory limit (or swap              limit) being reached, the allowed memory is that configured              limit.  Finally, if it is due to the entire system being out              of memory, the allowed memory represents all allocatable              resources.              The value of oom_score_adj is added to the badness score              before it is used to determine which task to kill.  Acceptable              values range from -1000 (OOM_SCORE_ADJ_MIN) to +1000              (OOM_SCORE_ADJ_MAX).  This allows user space to control the              preference for OOM-killing, ranging from always preferring a              certain task or completely disabling it from OOM killing.  The              lowest possible value, -1000, is equivalent to disabling OOM-              killing entirely for that task, since it will always report a              badness score of 0.              Consequently, it is very simple for user space to define the              amount of memory to consider for each task.  Setting a              oom_score_adj value of +500, for example, is roughly              equivalent to allowing the remainder of tasks sharing the same              system, cpuset, mempolicy, or memory controller resources to              use at least 50% more memory.  A value of -500, on the other              hand, would be roughly equivalent to discounting 50% of the              task's allowed memory from being considered as scoring against              the task.              For backward compatibility with previous kernels,              /proc/[pid]/oom_adj can still be used to tune the badness              score.  Its value is scaled linearly with oom_score_adj.              Writing to /proc/[pid]/oom_score_adj or /proc/[pid]/oom_adj              will change the other with its scaled value.       /proc/[pid]/pagemap (since Linux 2.6.25)              This file shows the mapping of each of the process's virtual              pages into physical page frames or swap area.  It contains one              64-bit value for each virtual page, with the bits set as              follows:                   63     If set, the page is present in RAM.                   62     If set, the page is in swap space                   61 (since Linux 3.5)                          The page is a file-mapped page or a shared                          anonymous page.                   60-56 (since Linux 3.11)                          Zero                   55 (Since Linux 3.11)                          PTE is soft-dirty (see the kernel source file                          Documentation/vm/soft-dirty.txt).                   54-0   If the page is present in RAM (bit 63), then these                          bits provide the page frame number, which can be                          used to index /proc/kpageflags and                          /proc/kpagecount.  If the page is present in swap                          (bit 62), then bits 4-0 give the swap type, and                          bits 54-5 encode the swap offset.              Before Linux 3.11, bits 60-55 were used to encode the base-2              log of the page size.              To employ /proc/[pid]/pagemap efficiently, use              /proc/[pid]/maps to determine which areas of memory are              actually mapped and seek to skip over unmapped regions.              The /proc/[pid]/pagemap file is present only if the              CONFIG_PROC_PAGE_MONITOR kernel configuration option is              enabled.       /proc/[pid]/personality (since Linux 2.6.28)              This read-only file exposes the process's execution domain, as              set by personality(2).  The value is displayed in hexadecimal              notation.       /proc/[pid]/root              UNIX and Linux support the idea of a per-process root of the              filesystem, set by the chroot(2) system call.  This file is a              symbolic link that points to the process's root directory, and              behaves in the same way as exe, and fd/*.              In a multithreaded process, the contents of this symbolic link              are not available if the main thread has already terminated              (typically by calling pthread_exit(3)).       /proc/[pid]/seccomp (from Linux 2.6.12 to 2.6.22)              Read/set the seccomp mode for the process.  If this file              contains the value zero, seccomp mode is not enabled.  Writing              the value 1 to this file (irreversibly) places the process in              seccomp mode: the only permitted system calls are read(2),              write(2), _exit(2), and sigreturn(2).  This file went away in              Linux 2.6.23, when it was replaced by a prctl(2)-based              mechanism.       /proc/[pid]/setgroups (since Linux 3.19)              See user_namespaces(7).       /proc/[pid]/smaps (since Linux 2.6.14)              This file shows memory consumption for each of the process's              mappings.  (The pmap(1) command displays similar information,              in a form that may be easier for parsing.)  For each mapping              there is a series of lines such as the following:                  00400000-0048a000 r-xp 00000000 fd:03 960637       /bin/bash                  Size:                552 kB                  Rss:                 460 kB                  Pss:                 100 kB                  Shared_Clean:        452 kB                  Shared_Dirty:          0 kB                  Private_Clean:         8 kB                  Private_Dirty:         0 kB                  Referenced:          460 kB                  Anonymous:             0 kB                  AnonHugePages:         0 kB                  Swap:                  0 kB                  KernelPageSize:        4 kB                  MMUPageSize:           4 kB                  Locked:                0 kB              The first of these lines shows the same information as is              displayed for the mapping in /proc/[pid]/maps.  The remaining              lines show the size of the mapping, the amount of the mapping              that is currently resident in RAM ("Rss"), the process'              proportional share of this mapping ("Pss"), the number of              clean and dirty shared pages in the mapping, and the number of              clean and dirty private pages in the mapping.  "Referenced"              indicates the amount of memory currently marked as referenced              or accessed.  "Anonymous" shows the amount of memory that does              not belong to any file.  "Swap" shows how much would-be-              anonymous memory is also used, but out on swap.              The "KernelPageSize" entry is the page size used by the kernel              to back a VMA.  This matches the size used by the MMU in the              majority of cases.  However, one counter-example occurs on              PPC64 kernels whereby a kernel using 64K as a base page size              may still use 4K pages for the MMU on older processors.  To              distinguish, this patch reports "MMUPageSize" as the page size              used by the MMU.              The "Locked" indicates whether the mapping is locked in memory              or not.              "VmFlags" field represents the kernel flags associated with              the particular virtual memory area in two letter encoded              manner.  The codes are the following:                  rd  - readable                  wr  - writable                  ex  - executable                  sh  - shared                  mr  - may read                  mw  - may write                  me  - may execute                  ms  - may share                  gd  - stack segment grows down                  pf  - pure PFN range                  dw  - disabled write to the mapped file                  lo  - pages are locked in memory                  io  - memory mapped I/O area                  sr  - sequential read advise provided                  rr  - random read advise provided                  dc  - do not copy area on fork                  de  - do not expand area on remapping                  ac  - area is accountable                  nr  - swap space is not reserved for the area                  ht  - area uses huge tlb pages                  nl  - non-linear mapping                  ar  - architecture specific flag                  dd  - do not include area into core dump                  sd  - soft-dirty flag                  mm  - mixed map area                  hg  - huge page advise flag                  nh  - no-huge page advise flag                  mg  - mergeable advise flag              The /proc/[pid]/smaps file is present only if the              CONFIG_PROC_PAGE_MONITOR kernel configuration option is              enabled.       /proc/[pid]/stack (since Linux 2.6.29)              This file provides a symbolic trace of the function calls in              this process's kernel stack.  This file is provided only if              the kernel was built with the CONFIG_STACKTRACE configuration              option.       /proc/[pid]/stat              Status information about the process.  This is used by ps(1).              It is defined in the kernel source file fs/proc/array.c.              The fields, in order, with their proper scanf(3) format              specifiers, are:              (1) pid  %d                        The process ID.              (2) comm  %s                        The filename of the executable, in parentheses.                        This is visible whether or not the executable is                        swapped out.              (3) state  %c                        One of the following characters, indicating process                        state:                        R  Running                        S  Sleeping in an interruptible wait                        D  Waiting in uninterruptible disk sleep                        Z  Zombie                        T  Stopped (on a signal) or (before Linux 2.6.33)                           trace stopped                        t  Tracing stop (Linux 2.6.33 onward)                        W  Paging (only before Linux 2.6.0)                        X  Dead (from Linux 2.6.0 onward)                        x  Dead (Linux 2.6.33 to 3.13 only)                        K  Wakekill (Linux 2.6.33 to 3.13 only)                        W  Waking (Linux 2.6.33 to 3.13 only)                        P  Parked (Linux 3.9 to 3.13 only)              (4) ppid  %d                        The PID of the parent of this process.              (5) pgrp  %d                        The process group ID of the process.              (6) session  %d                        The session ID of the process.              (7) tty_nr  %d                        The controlling terminal of the process.  (The minor                        device number is contained in the combination of                        bits 31 to 20 and 7 to 0; the major device number is                        in bits 15 to 8.)              (8) tpgid  %d                        The ID of the foreground process group of the                        controlling terminal of the process.              (9) flags  %u                        The kernel flags word of the process.  For bit                        meanings, see the PF_* defines in the Linux kernel                        source file include/linux/sched.h.  Details depend                        on the kernel version.                        The format for this field was %lu before Linux 2.6.              (10) minflt  %lu                        The number of minor faults the process has made                        which have not required loading a memory page from                        disk.              (11) cminflt  %lu                        The number of minor faults that the process's                        waited-for children have made.              (12) majflt  %lu                        The number of major faults the process has made                        which have required loading a memory page from disk.              (13) cmajflt  %lu                        The number of major faults that the process's                        waited-for children have made.              (14) utime  %lu                        Amount of time that this process has been scheduled                        in user mode, measured in clock ticks (divide by                        sysconf(_SC_CLK_TCK)).  This includes guest time,                        guest_time (time spent running a virtual CPU, see                        below), so that applications that are not aware of                        the guest time field do not lose that time from                        their calculations.              (15) stime  %lu                        Amount of time that this process has been scheduled                        in kernel mode, measured in clock ticks (divide by                        sysconf(_SC_CLK_TCK)).              (16) cutime  %ld                        Amount of time that this process's waited-for                        children have been scheduled in user mode, measured                        in clock ticks (divide by sysconf(_SC_CLK_TCK)).                        (See also times(2).)  This includes guest time,                        cguest_time (time spent running a virtual CPU, see                        below).              (17) cstime  %ld                        Amount of time that this process's waited-for                        children have been scheduled in kernel mode,                        measured in clock ticks (divide by                        sysconf(_SC_CLK_TCK)).              (18) priority  %ld                        (Explanation for Linux 2.6) For processes running a                        real-time scheduling policy (policy below; see                        sched_setscheduler(2)), this is the negated                        scheduling priority, minus one; that is, a number in                        the range -2 to -100, corresponding to real-time                        priorities 1 to 99.  For processes running under a                        non-real-time scheduling policy, this is the raw                        nice value (setpriority(2)) as represented in the                        kernel.  The kernel stores nice values as numbers in                        the range 0 (high) to 39 (low), corresponding to the                        user-visible nice range of -20 to 19.                        Before Linux 2.6, this was a scaled value based on                        the scheduler weighting given to this process.              (19) nice  %ld                        The nice value (see setpriority(2)), a value in the                        range 19 (low priority) to -20 (high priority).              (20) num_threads  %ld                        Number of threads in this process (since Linux 2.6).                        Before kernel 2.6, this field was hard coded to 0 as                        a placeholder for an earlier removed field.              (21) itrealvalue  %ld                        The time in jiffies before the next SIGALRM is sent                        to the process due to an interval timer.  Since                        kernel 2.6.17, this field is no longer maintained,                        and is hard coded as 0.              (22) starttime  %llu                        The time the process started after system boot.  In                        kernels before Linux 2.6, this value was expressed                        in jiffies.  Since Linux 2.6, the value is expressed                        in clock ticks (divide by sysconf(_SC_CLK_TCK)).                        The format for this field was %lu before Linux 2.6.              (23) vsize  %lu                        Virtual memory size in bytes.              (24) rss  %ld                        Resident Set Size: number of pages the process has                        in real memory.  This is just the pages which count                        toward text, data, or stack space.  This does not                        include pages which have not been demand-loaded in,                        or which are swapped out.              (25) rsslim  %lu                        Current soft limit in bytes on the rss of the                        process; see the description of RLIMIT_RSS in                        getrlimit(2).              (26) startcode  %lu                        The address above which program text can run.              (27) endcode  %lu                        The address below which program text can run.              (28) startstack  %lu                        The address of the start (i.e., bottom) of the                        stack.              (29) kstkesp  %lu                        The current value of ESP (stack pointer), as found                        in the kernel stack page for the process.              (30) kstkeip  %lu                        The current EIP (instruction pointer).              (31) signal  %lu                        The bitmap of pending signals, displayed as a                        decimal number.  Obsolete, because it does not                        provide information on real-time signals; use                        /proc/[pid]/status instead.              (32) blocked  %lu                        The bitmap of blocked signals, displayed as a                        decimal number.  Obsolete, because it does not                        provide information on real-time signals; use                        /proc/[pid]/status instead.              (33) sigignore  %lu                        The bitmap of ignored signals, displayed as a                        decimal number.  Obsolete, because it does not                        provide information on real-time signals; use                        /proc/[pid]/status instead.              (34) sigcatch  %lu                        The bitmap of caught signals, displayed as a decimal                        number.  Obsolete, because it does not provide                        information on real-time signals; use                        /proc/[pid]/status instead.              (35) wchan  %lu                        This is the "channel" in which the process is                        waiting.  It is the address of a location in the                        kernel where the process is sleeping.  The                        corresponding symbolic name can be found in                        /proc/[pid]/wchan.              (36) nswap  %lu                        Number of pages swapped (not maintained).              (37) cnswap  %lu                        Cumulative nswap for child processes (not                        maintained).              (38) exit_signal  %d  (since Linux 2.1.22)                        Signal to be sent to parent when we die.              (39) processor  %d  (since Linux 2.2.8)                        CPU number last executed on.              (40) rt_priority  %u  (since Linux 2.5.19)                        Real-time scheduling priority, a number in the range                        1 to 99 for processes scheduled under a real-time                        policy, or 0, for non-real-time processes (see                        sched_setscheduler(2)).              (41) policy  %u  (since Linux 2.5.19)                        Scheduling policy (see sched_setscheduler(2)).                        Decode using the SCHED_* constants in linux/sched.h.                        The format for this field was %lu before Linux                        2.6.22.              (42) delayacct_blkio_ticks  %llu  (since Linux 2.6.18)                        Aggregated block I/O delays, measured in clock ticks                        (centiseconds).              (43) guest_time  %lu  (since Linux 2.6.24)                        Guest time of the process (time spent running a                        virtual CPU for a guest operating system), measured                        in clock ticks (divide by sysconf(_SC_CLK_TCK)).              (44) cguest_time  %ld  (since Linux 2.6.24)                        Guest time of the process's children, measured in                        clock ticks (divide by sysconf(_SC_CLK_TCK)).              (45) start_data  %lu  (since Linux 3.3)                        Address above which program initialized and                        uninitialized (BSS) data are placed.              (46) end_data  %lu  (since Linux 3.3)                        Address below which program initialized and                        uninitialized (BSS) data are placed.              (47) start_brk  %lu  (since Linux 3.3)                        Address above which program heap can be expanded                        with brk(2).              (48) arg_start  %lu  (since Linux 3.5)                        Address above which program command-line arguments                        (argv) are placed.              (49) arg_end  %lu  (since Linux 3.5)                        Address below program command-line arguments (argv)                        are placed.              (50) env_start  %lu  (since Linux 3.5)                        Address above which program environment is placed.              (51) env_end  %lu  (since Linux 3.5)                        Address below which program environment is placed.              (52) exit_code  %d  (since Linux 3.5)                        The thread's exit status in the form reported by                        waitpid(2).       /proc/[pid]/statm              Provides information about memory usage, measured in pages.              The columns are:                  size       (1) total program size                             (same as VmSize in /proc/[pid]/status)                  resident   (2) resident set size                             (same as VmRSS in /proc/[pid]/status)                  share      (3) shared pages (i.e., backed by a file)                  text       (4) text (code)                  lib        (5) library (unused in Linux 2.6)                  data       (6) data + stack                  dt         (7) dirty pages (unused in Linux 2.6)       /proc/[pid]/status              Provides much of the information in /proc/[pid]/stat and              /proc/[pid]/statm in a format that's easier for humans to              parse.  Here's an example:                  $ cat /proc/$$/status                  Name:   bash                  State:  S (sleeping)                  Tgid:   3515                  Pid:    3515                  PPid:   3452                  TracerPid:      0                  Uid:    1000    1000    1000    1000                  Gid:    100     100     100     100                  FDSize: 256                  Groups: 16 33 100                  VmPeak:     9136 kB                  VmSize:     7896 kB                  VmLck:         0 kB                  VmPin:         0 kB                  VmHWM:      7572 kB                  VmRSS:      6316 kB                  VmData:     5224 kB                  VmStk:        88 kB                  VmExe:       572 kB                  VmLib:      1708 kB                  VmPTE:        20 kB                  VmSwap:        0 kB                  Threads:        1                  SigQ:   0/3067                  SigPnd: 0000000000000000                  ShdPnd: 0000000000000000                  SigBlk: 0000000000010000                  SigIgn: 0000000000384004                  SigCgt: 000000004b813efb                  CapInh: 0000000000000000                  CapPrm: 0000000000000000                  CapEff: 0000000000000000                  CapBnd: ffffffffffffffff                  Seccomp:        0                  Cpus_allowed:   00000001                  Cpus_allowed_list:      0                  Mems_allowed:   1                  Mems_allowed_list:      0                  voluntary_ctxt_switches:        150                  nonvoluntary_ctxt_switches:     545              The fields are as follows:              * Name: Command run by this process.              * State: Current state of the process.  One of "R (running)",                "S (sleeping)", "D (disk sleep)", "T (stopped)", "T (tracing                stop)", "Z (zombie)", or "X (dead)".              * Tgid: Thread group ID (i.e., Process ID).              * Pid: Thread ID (see gettid(2)).              * PPid: PID of parent process.              * TracerPid: PID of process tracing this process (0 if not                being traced).              * Uid, Gid: Real, effective, saved set, and filesystem UIDs                (GIDs).              * FDSize: Number of file descriptor slots currently allocated.              * Groups: Supplementary group list.              * VmPeak: Peak virtual memory size.              * VmSize: Virtual memory size.              * VmLck: Locked memory size (see mlock(3)).              * VmPin: Pinned memory size (since Linux 3.2).  These are                pages that can't be moved because something needs to                directly access physical memory.              * VmHWM: Peak resident set size ("high water mark").              * VmRSS: Resident set size.              * VmData, VmStk, VmExe: Size of data, stack, and text                segments.              * VmLib: Shared library code size.              * VmPTE: Page table entries size (since Linux 2.6.10).              * VmSwap: Swapped-out virtual memory size by anonymous private                pages; shmem swap usage is not included (since Linux                2.6.34).              * Threads: Number of threads in process containing this                thread.              * SigQ: This field contains two slash-separated numbers that                relate to queued signals for the real user ID of this                process.  The first of these is the number of currently                queued signals for this real user ID, and the second is the                resource limit on the number of queued signals for this                process (see the description of RLIMIT_SIGPENDING in                getrlimit(2)).              * SigPnd, ShdPnd: Number of signals pending for thread and for                process as a whole (see pthreads(7) and signal(7)).              * SigBlk, SigIgn, SigCgt: Masks indicating signals being                blocked, ignored, and caught (see signal(7)).              * CapInh, CapPrm, CapEff: Masks of capabilities enabled in                inheritable, permitted, and effective sets (see                capabilities(7)).              * CapBnd: Capability Bounding set (since Linux 2.6.26, see                capabilities(7)).              * Seccomp: Seccomp mode of the process (since Linux 3.8, see                seccomp(2)).  0 means SECCOMP_MODE_DISABLED; 1 means                SECCOMP_MODE_STRICT; 2 means SECCOMP_MODE_FILTER.  This                field is provided only if the kernel was built with the                CONFIG_SECCOMP kernel configuration option enabled.              * Cpus_allowed: Mask of CPUs on which this process may run                (since Linux 2.6.24, see cpuset(7)).              * Cpus_allowed_list: Same as previous, but in "list format"                (since Linux 2.6.26, see cpuset(7)).              * Mems_allowed: Mask of memory nodes allowed to this process                (since Linux 2.6.24, see cpuset(7)).              * Mems_allowed_list: Same as previous, but in "list format"                (since Linux 2.6.26, see cpuset(7)).              * voluntary_ctxt_switches, nonvoluntary_ctxt_switches: Number                of voluntary and involuntary context switches (since Linux                2.6.23).       /proc/[pid]/syscall (since Linux 2.6.27)              This file exposes the system call number and argument              registers for the system call currently being executed by the              process, followed by the values of the stack pointer and              program counter registers.  The values of all six argument              registers are exposed, although most system calls use fewer              registers.              If the process is blocked, but not in a system call, then the              file displays -1 in place of the system call number, followed              by just the values of the stack pointer and program counter.              If process is not blocked, then file contains just the string              "running".              This file is present only if the kernel was configured with              CONFIG_HAVE_ARCH_TRACEHOOK.       /proc/[pid]/task (since Linux 2.6.0-test6)              This is a directory that contains one subdirectory for each              thread in the process.  The name of each subdirectory is the              numerical thread ID ([tid]) of the thread (see gettid(2)).              Within each of these subdirectories, there is a set of files              with the same names and contents as under the /proc/[pid]              directories.  For attributes that are shared by all threads,              the contents for each of the files under the task/[tid]              subdirectories will be the same as in the corresponding file              in the parent /proc/[pid] directory (e.g., in a multithreaded              process, all of the task/[tid]/cwd files will have the same              value as the /proc/[pid]/cwd file in the parent directory,              since all of the threads in a process share a working              directory).  For attributes that are distinct for each thread,              the corresponding files under task/[tid] may have different              values (e.g., various fields in each of the task/[tid]/status              files may be different for each thread).              In a multithreaded process, the contents of the              /proc/[pid]/task directory are not available if the main              thread has already terminated (typically by calling              pthread_exit(3)).       /proc/[pid]/uid_map, /proc/[pid]/gid_map (since Linux 3.5)              See user_namespaces(7).       /proc/[pid]/wchan (since Linux 2.6.0)              The symbolic name corresponding to the location in the kernel              where the process is sleeping.       /proc/apm              Advanced power management version and battery information when              CONFIG_APM is defined at kernel compilation time.       /proc/buddyinfo              This file contains information which is used for diagnosing              memory fragmentation issues.  Each line starts with the              identification of the node and the name of the zone which              together identify a memory region This is then followed by the              count of available chunks of a certain order in which these              zones are split.  The size in bytes of a certain order is              given by the formula:                  (2^order) * PAGE_SIZE              The binary buddy allocator algorithm inside the kernel will              split one chunk into two chunks of a smaller order (thus with              half the size) or combine two contiguous chunks into one              larger chunk of a higher order (thus with double the size) to              satisfy allocation requests and to counter memory              fragmentation.  The order matches the column number, when              starting to count at zero.              For example on a x86_64 system:  Node 0, zone     DMA     1    1    1    0    2    1    1    0    1    1    3  Node 0, zone   DMA32    65   47    4   81   52   28   13   10    5    1  404  Node 0, zone  Normal   216   55  189  101   84   38   37   27    5    3  587              In this example, there is one node containing three zones and              there are 11 different chunk sizes.  If the page size is 4              kilobytes, then the first zone called DMA (on x86 the first 16              megabyte of memory) has 1 chunk of 4 kilobytes (order 0)              available and has 3 chunks of 4 megabytes (order 10)              available.              If the memory is heavily fragmented, the counters for higher              order chunks will be zero and allocation of large contiguous              areas will fail.              Further information about the zones can be found in              /proc/zoneinfo.       /proc/bus              Contains subdirectories for installed busses.       /proc/bus/pccard              Subdirectory for PCMCIA devices when CONFIG_PCMCIA is set at              kernel compilation time.       /proc/[pid]/timers (since Linux 3.10)              A list of the POSIX timers for this process.  Each timer is              listed with a line that starts with the string "ID:".  For              example:                  ID: 1                  signal: 60/00007fff86e452a8                  notify: signal/pid.2634                  ClockID: 0                  ID: 0                  signal: 60/00007fff86e452a8                  notify: signal/pid.2634                  ClockID: 1              The lines shown for each timer have the following meanings:              ID     The ID for this timer.  This is not the same as the                     timer ID returned by timer_create(2); rather, it is the                     same kernel-internal ID that is available via the                     si_timerid field of the siginfo_t structure (see                     sigaction(2)).              signal This is the signal number that this timer uses to                     deliver notifications followed by a slash, and then the                     sigev_value value supplied to the signal handler.                     Valid only for timers that notify via a signal.              notify The part before the slash specifies the mechanism that                     this timer uses to deliver notifications, and is one of                     "thread", "signal", or "none".  Immediately following                     the slash is either the string "tid" for timers with                     SIGEV_THREAD_ID notification, or "pid" for timers that                     notify by other mechanisms.  Following the "." is the                     PID of the process (or the kernel thread ID of the                     thread)  that will be delivered a signal if the timer                     delivers notifications via a signal.              ClockID                     This field identifies the clock that the timer uses for                     measuring time.  For most clocks, this is a number that                     matches one of the user-space CLOCK_* constants exposed                     via <time.h>.  CLOCK_PROCESS_CPUTIME_ID timers display                     with a value of -6 in this field.                     CLOCK_THREAD_CPUTIME_ID timers display with a value of                     -2 in this field.              This file is available only when the kernel was configured              with CONFIG_CHECKPOINT_RESTORE.       /proc/bus/pccard/drivers       /proc/bus/pci              Contains various bus subdirectories and pseudo-files              containing information about PCI busses, installed devices,              and device drivers.  Some of these files are not ASCII.       /proc/bus/pci/devices              Information about PCI devices.  They may be accessed through              lspci(8) and setpci(8).       /proc/cmdline              Arguments passed to the Linux kernel at boot time.  Often done              via a boot manager such as lilo(8) or grub(8).       /proc/config.gz (since Linux 2.6)              This file exposes the configuration options that were used to              build the currently running kernel, in the same format as they              would be shown in the .config file that resulted when              configuring the kernel (using make xconfig, make config, or              similar).  The file contents are compressed; view or search              them using zcat(1) and zgrep(1).  As long as no changes have              been made to the following file, the contents of              /proc/config.gz are the same as those provided by :                  cat /lib/modules/$(uname -r)/build/.config              /proc/config.gz is provided only if the kernel is configured              with CONFIG_IKCONFIG_PROC.       /proc/cpuinfo              This is a collection of CPU and system architecture dependent              items, for each supported architecture a different list.  Two              common entries are processor which gives CPU number and              bogomips; a system constant that is calculated during kernel              initialization.  SMP machines have information for each CPU.              The lscpu(1) command gathers its information from this file.       /proc/devices              Text listing of major numbers and device groups.  This can be              used by MAKEDEV scripts for consistency with the kernel.       /proc/diskstats (since Linux 2.5.69)              This file contains disk I/O statistics for each disk device.              See the Linux kernel source file Documentation/iostats.txt for              further information.       /proc/dma              This is a list of the registered ISA DMA (direct memory              access) channels in use.       /proc/driver              Empty subdirectory.       /proc/execdomains              List of the execution domains (ABI personalities).       /proc/fb              Frame buffer information when CONFIG_FB is defined during              kernel compilation.       /proc/filesystems              A text listing of the filesystems which are supported by the              kernel, namely filesystems which were compiled into the kernel              or whose kernel modules are currently loaded.  (See also              filesystems(5).)  If a filesystem is marked with "nodev", this              means that it does not require a block device to be mounted              (e.g., virtual filesystem, network filesystem).              Incidentally, this file may be used by mount(8) when no              filesystem is specified and it didn't manage to determine the              filesystem type.  Then filesystems contained in this file are              tried (excepted those that are marked with "nodev").       /proc/fs              Contains subdirectories that in turn contain files with              information about (certain) mounted filesystems.       /proc/ide              This directory exists on systems with the IDE bus.  There are              directories for each IDE channel and attached device.  Files              include:                  cache              buffer size in KB                  capacity           number of sectors                  driver             driver version                  geometry           physical and logical geometry                  identify           in hexadecimal                  media              media type                  model              manufacturer's model number                  settings           drive settings                  smart_thresholds   in hexadecimal                  smart_values       in hexadecimal              The hdparm(8) utility provides access to this information in a              friendly format.       /proc/interrupts              This is used to record the number of interrupts per CPU per IO              device.  Since Linux 2.6.24, for the i386 and x86_64              architectures, at least, this also includes interrupts              internal to the system (that is, not associated with a device              as such), such as NMI (nonmaskable interrupt), LOC (local              timer interrupt), and for SMP systems, TLB (TLB flush              interrupt), RES (rescheduling interrupt), CAL (remote function              call interrupt), and possibly others.  Very easy to read              formatting, done in ASCII.       /proc/iomem              I/O memory map in Linux 2.4.       /proc/ioports              This is a list of currently registered Input-Output port              regions that are in use.       /proc/kallsyms (since Linux 2.5.71)              This holds the kernel exported symbol definitions used by the              modules(X) tools to dynamically link and bind loadable              modules.  In Linux 2.5.47 and earlier, a similar file with              slightly different syntax was named ksyms.       /proc/kcore              This file represents the physical memory of the system and is              stored in the ELF core file format.  With this pseudo-file,              and an unstripped kernel (/usr/src/linux/vmlinux) binary, GDB              can be used to examine the current state of any kernel data              structures.              The total length of the file is the size of physical memory              (RAM) plus 4KB.       /proc/kmsg              This file can be used instead of the syslog(2) system call to              read kernel messages.  A process must have superuser              privileges to read this file, and only one process should read              this file.  This file should not be read if a syslog process              is running which uses the syslog(2) system call facility to              log kernel messages.              Information in this file is retrieved with the dmesg(1)              program.       /proc/kpagecount (since Linux 2.6.25)              This file contains a 64-bit count of the number of times each              physical page frame is mapped, indexed by page frame number              (see the discussion of /proc/[pid]/pagemap).              The /proc/kpagecount file is present only if the              CONFIG_PROC_PAGE_MONITOR kernel configuration option is              enabled.       /proc/kpageflags (since Linux 2.6.25)              This file contains 64-bit masks corresponding to each physical              page frame; it is indexed by page frame number (see the              discussion of /proc/[pid]/pagemap).  The bits are as follows:                   0 - KPF_LOCKED                   1 - KPF_ERROR                   2 - KPF_REFERENCED                   3 - KPF_UPTODATE                   4 - KPF_DIRTY                   5 - KPF_LRU                   6 - KPF_ACTIVE                   7 - KPF_SLAB                   8 - KPF_WRITEBACK                   9 - KPF_RECLAIM                  10 - KPF_BUDDY                  11 - KPF_MMAP           (since Linux 2.6.31)                  12 - KPF_ANON           (since Linux 2.6.31)                  13 - KPF_SWAPCACHE      (since Linux 2.6.31)                  14 - KPF_SWAPBACKED     (since Linux 2.6.31)                  15 - KPF_COMPOUND_HEAD  (since Linux 2.6.31)                  16 - KPF_COMPOUND_TAIL  (since Linux 2.6.31)                  16 - KPF_HUGE           (since Linux 2.6.31)                  18 - KPF_UNEVICTABLE    (since Linux 2.6.31)                  19 - KPF_HWPOISON       (since Linux 2.6.31)                  20 - KPF_NOPAGE         (since Linux 2.6.31)                  21 - KPF_KSM            (since Linux 2.6.32)                  22 - KPF_THP            (since Linux 3.4)              For further details on the meanings of these bits, see the              kernel source file Documentation/vm/pagemap.txt.  Before              kernel 2.6.29, KPF_WRITEBACK, KPF_RECLAIM, KPF_BUDDY, and              KPF_LOCKED did not report correctly.              The /proc/kpageflags file is present only if the              CONFIG_PROC_PAGE_MONITOR kernel configuration option is              enabled.       /proc/ksyms (Linux 1.1.23-2.5.47)              See /proc/kallsyms.       /proc/loadavg              The first three fields in this file are load average figures              giving the number of jobs in the run queue (state R) or              waiting for disk I/O (state D) averaged over 1, 5, and 15              minutes.  They are the same as the load average numbers given              by uptime(1) and other programs.  The fourth field consists of              two numbers separated by a slash (/).  The first of these is              the number of currently runnable kernel scheduling entities              (processes, threads).  The value after the slash is the number              of kernel scheduling entities that currently exist on the              system.  The fifth field is the PID of the process that was              most recently created on the system.       /proc/locks              This file shows current file locks (flock(2) and fcntl(2)) and              leases (fcntl(2)).       /proc/malloc (only up to and including Linux 2.2)              This file is present only if CONFIG_DEBUG_MALLOC was defined              during compilation.       /proc/meminfo              This file reports statistics about memory usage on the system.              It is used by free(1) to report the amount of free and used              memory (both physical and swap) on the system as well as the              shared memory and buffers used by the kernel.  Each line of              the file consists of a parameter name, followed by a colon,              the value of the parameter, and an option unit of measurement              (e.g., "kB").  The list below describes the parameter names              and the format specifier required to read the field value.              Except as noted below, all of the fields have been present              since at least Linux 2.6.0.  Some fields are displayed only if              the kernel was configured with various options; those              dependencies are noted in the list.              MemTotal %lu                     Total usable RAM (i.e., physical RAM minus a few                     reserved bits and the kernel binary code).              MemFree %lu                     The sum of LowFree+HighFree.              Buffers %lu                     Relatively temporary storage for raw disk blocks that                     shouldn't get tremendously large (20MB or so).              Cached %lu                     In-memory cache for files read from the disk (the page                     cache).  Doesn't include SwapCached.              SwapCached %lu                     Memory that once was swapped out, is swapped back in                     but still also is in the swap file.  (If memory                     pressure is high, these pages don't need to be swapped                     out again because they are already in the swap file.                     This saves I/O.)              Active %lu                     Memory that has been used more recently and usually not                     reclaimed unless absolutely necessary.              Inactive %lu                     Memory which has been less recently used.  It is more                     eligible to be reclaimed for other purposes.              Active(anon) %lu (since Linux 2.6.28)                     [To be documented.]              Inactive(anon) %lu (since Linux 2.6.28)                     [To be documented.]              Active(file) %lu (since Linux 2.6.28)                     [To be documented.]              Inactive(file) %lu (since Linux 2.6.28)                     [To be documented.]              Unevictable %lu (since Linux 2.6.28)                     (From Linux 2.6.28 to 2.6.30, CONFIG_UNEVICTABLE_LRU                     was required.)  [To be documented.]              Mlocked %lu (since Linux 2.6.28)                     (From Linux 2.6.28 to 2.6.30, CONFIG_UNEVICTABLE_LRU                     was required.)  [To be documented.]              HighTotal %lu                     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is                     required.)  Total amount of highmem.  Highmem is all                     memory above ~860MB of physical memory.  Highmem areas                     are for use by user-space programs, or for the page                     cache.  The kernel must use tricks to access this                     memory, making it slower to access than lowmem.              HighFree %lu                     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is                     required.)  Amount of free highmem.              LowTotal %lu                     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is                     required.)  Total amount of lowmem.  Lowmem is memory                     which can be used for everything that highmem can be                     used for, but it is also available for the kernel's use                     for its own data structures.  Among many other things,                     it is where everything from Slab is allocated.  Bad                     things happen when you're out of lowmem.              LowFree %lu                     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is                     required.)  Amount of free lowmem.              MmapCopy %lu (since Linux 2.6.29)                     (CONFIG_MMU is required.)  [To be documented.]              SwapTotal %lu                     Total amount of swap space available.              SwapFree %lu                     Amount of swap space that is currently unused.              Dirty %lu                     Memory which is waiting to get written back to the                     disk.              Writeback %lu                     Memory which is actively being written back to the                     disk.              AnonPages %lu (since Linux 2.6.18)                     Non-file backed pages mapped into user-space page                     tables.              Mapped %lu                     Files which have been mapped into memory (with                     mmap(2)), such as libraries.              Shmem %lu (since Linux 2.6.32)                     [To be documented.]              Slab %lu                     In-kernel data structures cache.              SReclaimable %lu (since Linux 2.6.19)                     Part of Slab, that might be reclaimed, such as caches.              SUnreclaim %lu (since Linux 2.6.19)                     Part of Slab, that cannot be reclaimed on memory                     pressure.              KernelStack %lu (since Linux 2.6.32)                     Amount of memory allocated to kernel stacks.              PageTables %lu (since Linux 2.6.18)                     Amount of memory dedicated to the lowest level of page                     tables.              Quicklists %lu (since Linux 2.6.27)                     (CONFIG_QUICKLIST is required.)  [To be documented.]              NFS_Unstable %lu (since Linux 2.6.18)                     NFS pages sent to the server, but not yet committed to                     stable storage.              Bounce %lu (since Linux 2.6.18)                     Memory used for block device "bounce buffers".              WritebackTmp %lu (since Linux 2.6.26)                     Memory used by FUSE for temporary writeback buffers.              CommitLimit %lu (since Linux 2.6.10)                     This is the total amount of memory currently available                     to be allocated on the system, expressed in kilobytes.                     This limit is adhered to only if strict overcommit                     accounting is enabled (mode 2 in                     /proc/sys/vm/overcommit_memory).  The limit is                     calculated according to the formula described under                     /proc/sys/vm/overcommit_memory.  For further details,                     see the kernel source file Documentation/vm/overcommit-                     accounting.              Committed_AS %lu                     The amount of memory presently allocated on the system.                     The committed memory is a sum of all of the memory                     which has been allocated by processes, even if it has                     not been "used" by them as of yet.  A process which                     allocates 1GB of memory (using malloc(3) or similar),                     but touches only 300MB of that memory will show up as                     using only 300MB of memory even if it has the address                     space allocated for the entire 1GB.                     This 1GB is memory which has been "committed" to by the                     VM and can be used at any time by the allocating                     application.  With strict overcommit enabled on the                     system (mode 2 in IR /proc/sys/vm/overcommit_memory ),                     allocations which would exceed the CommitLimit will not                     be permitted.  This is useful if one needs to guarantee                     that processes will not fail due to lack of memory once                     that memory has been successfully allocated.              VmallocTotal %lu                     Total size of vmalloc memory area.              VmallocUsed %lu                     Amount of vmalloc area which is used.              VmallocChunk %lu                     Largest contiguous block of vmalloc area which is free.              HardwareCorrupted %lu (since Linux 2.6.32)                     (CONFIG_MEMORY_FAILURE is required.)  [To be                     documented.]              AnonHugePages %lu (since Linux 2.6.38)                     (CONFIG_TRANSPARENT_HUGEPAGE is required.)  Non-file                     backed huge pages mapped into user-space page tables.              HugePages_Total %lu                     (CONFIG_HUGETLB_PAGE is required.)  The size of the                     pool of huge pages.              HugePages_Free %lu                     (CONFIG_HUGETLB_PAGE is required.)  The number of huge                     pages in the pool that are not yet allocated.              HugePages_Rsvd %lu (since Linux 2.6.17)                     (CONFIG_HUGETLB_PAGE is required.)  This is the number                     of huge pages for which a commitment to allocate from                     the pool has been made, but no allocation has yet been                     made.  These reserved huge pages guarantee that an                     application will be able to allocate a huge page from                     the pool of huge pages at fault time.              HugePages_Surp %lu (since Linux 2.6.24)                     (CONFIG_HUGETLB_PAGE is required.)  This is the number                     of huge pages in the pool above the value in                     /proc/sys/vm/nr_hugepages.  The maximum number of                     surplus huge pages is controlled by                     /proc/sys/vm/nr_overcommit_hugepages.              Hugepagesize %lu                     (CONFIG_HUGETLB_PAGE is required.)  The size of huge                     pages.       /proc/modules              A text list of the modules that have been loaded by the              system.  See also lsmod(8).       /proc/mounts              Before kernel 2.4.19, this file was a list of all the              filesystems currently mounted on the system.  With the              introduction of per-process mount namespaces in Linux 2.4.19,              this file became a link to /proc/self/mounts, which lists the              mount points of the process's own mount namespace.  The format              of this file is documented in fstab(5).       /proc/mtrr              Memory Type Range Registers.  See the Linux kernel source file              Documentation/mtrr.txt for details.       /proc/net              various net pseudo-files, all of which give the status of some              part of the networking layer.  These files contain ASCII              structures and are, therefore, readable with cat(1).  However,              the standard netstat(8) suite provides much cleaner access to              these files.       /proc/net/arp              This holds an ASCII readable dump of the kernel ARP table used              for address resolutions.  It will show both dynamically              learned and preprogrammed ARP entries.  The format is:        IP address     HW type   Flags     HW address          Mask   Device        192.168.0.50   0x1       0x2       00:50:BF:25:68:F3   *      eth0        192.168.0.250  0x1       0xc       00:00:00:00:00:00   *      eth0              Here "IP address" is the IPv4 address of the machine and the              "HW type" is the hardware type of the address from RFC 826.              The flags are the internal flags of the ARP structure (as              defined in /usr/include/linux/if_arp.h) and the "HW address"              is the data link layer mapping for that IP address if it is              known.       /proc/net/dev              The dev pseudo-file contains network device status              information.  This gives the number of received and sent              packets, the number of errors and collisions and other basic              statistics.  These are used by the ifconfig(8) program to              report device status.  The format is: Inter-|   Receive                                                |  Transmit  face |bytes    packets errs drop fifo frame compressed multicast|bytes    packets errs drop fifo colls carrier compressed     lo: 2776770   11307    0    0    0     0          0         0  2776770   11307    0    0    0     0       0          0   eth0: 1215645    2751    0    0    0     0          0         0  1782404    4324    0    0    0   427       0          0   ppp0: 1622270    5552    1    0    0     0          0         0   354130    5669    0    0    0     0       0          0   tap0:    7714      81    0    0    0     0          0         0     7714      81    0    0    0     0       0          0       /proc/net/dev_mcast              Defined in /usr/src/linux/net/core/dev_mcast.c:                   indx interface_name  dmi_u dmi_g dmi_address                   2    eth0            1     0     01005e000001                   3    eth1            1     0     01005e000001                   4    eth2            1     0     01005e000001       /proc/net/igmp              Internet Group Management Protocol.  Defined in              /usr/src/linux/net/core/igmp.c.       /proc/net/rarp              This file uses the same format as the arp file and contains              the current reverse mapping database used to provide rarp(8)              reverse address lookup services.  If RARP is not configured              into the kernel, this file will not be present.       /proc/net/raw              Holds a dump of the RAW socket table.  Much of the information              is not of use apart from debugging.  The "sl" value is the              kernel hash slot for the socket, the "local_address" is the              local address and protocol number pair.  "St" is the internal              status of the socket.  The "tx_queue" and "rx_queue" are the              outgoing and incoming data queue in terms of kernel memory              usage.  The "tr", "tm->when", and "rexmits" fields are not              used by RAW.  The "uid" field holds the effective UID of the              creator of the socket.       /proc/net/snmp              This file holds the ASCII data needed for the IP, ICMP, TCP,              and UDP management information bases for an SNMP agent.       /proc/net/tcp              Holds a dump of the TCP socket table.  Much of the information              is not of use apart from debugging.  The "sl" value is the              kernel hash slot for the socket, the "local_address" is the              local address and port number pair.  The "rem_address" is the              remote address and port number pair (if connected).  "St" is              the internal status of the socket.  The "tx_queue" and              "rx_queue" are the outgoing and incoming data queue in terms              of kernel memory usage.  The "tr", "tm->when", and "rexmits"              fields hold internal information of the kernel socket state              and are useful only for debugging.  The "uid" field holds the              effective UID of the creator of the socket.       /proc/net/udp              Holds a dump of the UDP socket table.  Much of the information              is not of use apart from debugging.  The "sl" value is the              kernel hash slot for the socket, the "local_address" is the              local address and port number pair.  The "rem_address" is the              remote address and port number pair (if connected). "St" is              the internal status of the socket.  The "tx_queue" and              "rx_queue" are the outgoing and incoming data queue in terms              of kernel memory usage.  The "tr", "tm->when", and "rexmits"              fields are not used by UDP.  The "uid" field holds the              effective UID of the creator of the socket.  The format is: sl  local_address rem_address   st tx_queue rx_queue tr rexmits  tm->when uid  1: 01642C89:0201 0C642C89:03FF 01 00000000:00000001 01:000071BA 00000000 0  1: 00000000:0801 00000000:0000 0A 00000000:00000000 00:00000000 6F000100 0  1: 00000000:0201 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0       /proc/net/unix              Lists the UNIX domain sockets present within the system and              their status.  The format is:              Num RefCount Protocol Flags    Type St Path               0: 00000002 00000000 00000000 0001 03               1: 00000001 00000000 00010000 0001 01 /dev/printer              The fields are as follows:              Num:      the kernel table slot number.              RefCount: the number of users of the socket.              Protocol: currently always 0.              Flags:    the internal kernel flags holding the status of the                        socket.              Type:     the socket type.  For SOCK_STREAM sockets, this is                        0001; for SOCK_DGRAM sockets, it is 0002; and for                        SOCK_SEQPACKET sockets, it is 0005.              St:       the internal state of the socket.              Path:     the bound path (if any) of the socket.  Sockets in                        the abstract namespace are included in the list, and                        are shown with a Path that commences with the                        character '@'.       /proc/net/netfilter/nfnetlink_queue              This file contains information about netfilter userspace              queueing, if used.  Each line represents a queue.  Queues that              have not been subscribed to by userspace are not shown.                 1   4207     0  2 65535     0     0        0  1                (1)   (2)    (3)(4)  (5)    (6)   (7)      (8)              The fields in each line are:              (1)  The ID of the queue.  This matches what is specified in                   the --queue-num or --queue-balance options to the                   iptables(8) NFQUEUE target.  See iptables-extensions(8)                   for more information.              (2)  The netlink port ID subscribed to the queue.              (3)  The number of packets currently queued and waiting to be                   processed by the application.              (4)  The copy mode of the queue. It is either 1 (metadata                   only) or 2 (also copy payload data to userspace).              (5)  Copy range, i.e. how many bytes of packet payload should                   be copied to userspace at most.              (6)  queue dropped.  Number of packets that had to be dropped                   by the kernel because too many packets are already                   waiting for userspace to send back the mandatory                   accept/drop verdicts.              (7)  queue user dropped.  Number of packets that were dropped                   within the netlink subsystem.  Such drops usually happen                   when the corresponding socket buffer is full, i.e.                   userspace is not able to read messages fast enough.              (8)  sequence number. Every queued packet is associated with a                   (32-bit) monotonically-increasing sequence number.  This                   shows the ID of the most recent packet queued.              The last number exists only for compatibility reasons and is              always 1.       /proc/partitions              Contains the major and minor numbers of each partition as well              as the number of 1024-byte blocks and the partition name.       /proc/pci              This is a listing of all PCI devices found during kernel              initialization and their configuration.              This file has been deprecated in favor of a new /proc              interface for PCI (/proc/bus/pci).  It became optional in              Linux 2.2 (available with CONFIG_PCI_OLD_PROC set at kernel              compilation).  It became once more nonoptionally enabled in              Linux 2.4.  Next, it was deprecated in Linux 2.6 (still              available with CONFIG_PCI_LEGACY_PROC set), and finally              removed altogether since Linux 2.6.17.       /proc/profile (since Linux 2.4)              This file is present only if the kernel was booted with the              profile=1 command-line option.  It exposes kernel profiling              information in a binary format for use by readprofile(1).              Writing (e.g., an empty string) to this file resets the              profiling counters; on some architectures, writing a binary              integer "profiling multiplier" of size sizeof(int) sets the              profiling interrupt frequency.       /proc/scsi              A directory with the scsi mid-level pseudo-file and various              SCSI low-level driver directories, which contain a file for              each SCSI host in this system, all of which give the status of              some part of the SCSI IO subsystem.  These files contain ASCII              structures and are, therefore, readable with cat(1).              You can also write to some of the files to reconfigure the              subsystem or switch certain features on or off.       /proc/scsi/scsi              This is a listing of all SCSI devices known to the kernel.              The listing is similar to the one seen during bootup.  scsi              currently supports only the add-single-device command which              allows root to add a hotplugged device to the list of known              devices.              The command                  echo 'scsi add-single-device 1 0 5 0' > /proc/scsi/scsi              will cause host scsi1 to scan on SCSI channel 0 for a device              on ID 5 LUN 0.  If there is already a device known on this              address or the address is invalid, an error will be returned.       /proc/scsi/[drivername]              [drivername] can currently be NCR53c7xx, aha152x, aha1542,              aha1740, aic7xxx, buslogic, eata_dma, eata_pio, fdomain,              in2000, pas16, qlogic, scsi_debug, seagate, t128, u15-24f,              ultrastore, or wd7000.  These directories show up for all              drivers that registered at least one SCSI HBA.  Every              directory contains one file per registered host.  Every host-              file is named after the number the host was assigned during              initialization.              Reading these files will usually show driver and host              configuration, statistics, and so on.              Writing to these files allows different things on different              hosts.  For example, with the latency and nolatency commands,              root can switch on and off command latency measurement code in              the eata_dma driver.  With the lockup and unlock commands,              root can control bus lockups simulated by the scsi_debug              driver.       /proc/self              This directory refers to the process accessing the /proc              filesystem, and is identical to the /proc directory named by              the process ID of the same process.       /proc/slabinfo              Information about kernel caches.  Since Linux 2.6.16 this file              is present only if the CONFIG_SLAB kernel configuration option              is enabled.  The columns in /proc/slabinfo are:                  cache-name                  num-active-objs                  total-objs                  object-size                  num-active-slabs                  total-slabs                  num-pages-per-slab              See slabinfo(5) for details.       /proc/stat              kernel/system statistics.  Varies with architecture.  Common              entries include:              cpu  3357 0 4313 1362393                     The amount of time, measured in units of USER_HZ                     (1/100ths of a second on most architectures, use                     sysconf(_SC_CLK_TCK) to obtain the right value), that                     the system spent in various states:                     user   (1) Time spent in user mode.                     nice   (2) Time spent in user mode with low priority                            (nice).                     system (3) Time spent in system mode.                     idle   (4) Time spent in the idle task.  This value                            should be USER_HZ times the second entry in the                            /proc/uptime pseudo-file.                     iowait (since Linux 2.5.41)                            (5) Time waiting for I/O to complete.                     irq (since Linux 2.6.0-test4)                            (6) Time servicing interrupts.                     softirq (since Linux 2.6.0-test4)                            (7) Time servicing softirqs.                     steal (since Linux 2.6.11)                            (8) Stolen time, which is the time spent in                            other operating systems when running in a                            virtualized environment                     guest (since Linux 2.6.24)                            (9) Time spent running a virtual CPU for guest                            operating systems under the control of the Linux                            kernel.                     guest_nice (since Linux 2.6.33)                            (10) Time spent running a niced guest (virtual                            CPU for guest operating systems under the                            control of the Linux kernel).              page 5741 1808                     The number of pages the system paged in and the number                     that were paged out (from disk).              swap 1 0                     The number of swap pages that have been brought in and                     out.              intr 1462898                     This line shows counts of interrupts serviced since                     boot time, for each of the possible system interrupts.                     The first column is the total of all interrupts                     serviced including unnumbered architecture specific                     interrupts; each subsequent column is the total for                     that particular numbered interrupt.  Unnumbered                     interrupts are not shown, only summed into the total.              disk_io: (2,0):(31,30,5764,1,2) (3,0):...                     (major,disk_idx):(noinfo, read_io_ops, blks_read,                     write_io_ops, blks_written)                     (Linux 2.4 only)              ctxt 115315                     The number of context switches that the system                     underwent.              btime 769041601                     boot time, in seconds since the Epoch, 1970-01-01                     00:00:00 +0000 (UTC).              processes 86031                     Number of forks since boot.              procs_running 6                     Number of processes in runnable state.  (Linux 2.5.45                     onward.)              procs_blocked 2                     Number of processes blocked waiting for I/O to                     complete.  (Linux 2.5.45 onward.)       /proc/swaps              Swap areas in use.  See also swapon(8).       /proc/sys              This directory (present since 1.3.57) contains a number of              files and subdirectories corresponding to kernel variables.              These variables can be read and sometimes modified using the              /proc filesystem, and the (deprecated) sysctl(2) system call.       /proc/sys/abi (since Linux 2.4.10)              This directory may contain files with application binary              information.  See the Linux kernel source file              Documentation/sysctl/abi.txt for more information.       /proc/sys/debug              This directory may be empty.       /proc/sys/dev              This directory contains device-specific information (e.g.,              dev/cdrom/info).  On some systems, it may be empty.       /proc/sys/fs              This directory contains the files and subdirectories for              kernel variables related to filesystems.       /proc/sys/fs/binfmt_misc              Documentation for files in this directory can be found in the              Linux kernel sources in Documentation/binfmt_misc.txt.       /proc/sys/fs/dentry-state (since Linux 2.2)              This file contains information about the status of the              directory cache (dcache).  The file contains six numbers,              nr_dentry, nr_unused, age_limit (age in seconds), want_pages              (pages requested by system) and two dummy values.              * nr_dentry is the number of allocated dentries (dcache                entries).  This field is unused in Linux 2.2.              * nr_unused is the number of unused dentries.              * age_limit is the age in seconds after which dcache entries                can be reclaimed when memory is short.              * want_pages is nonzero when the kernel has called                shrink_dcache_pages() and the dcache isn't pruned yet.       /proc/sys/fs/dir-notify-enable              This file can be used to disable or enable the dnotify              interface described in fcntl(2) on a system-wide basis.  A              value of 0 in this file disables the interface, and a value of              1 enables it.       /proc/sys/fs/dquot-max              This file shows the maximum number of cached disk quota              entries.  On some (2.4) systems, it is not present.  If the              number of free cached disk quota entries is very low and you              have some awesome number of simultaneous system users, you              might want to raise the limit.       /proc/sys/fs/dquot-nr              This file shows the number of allocated disk quota entries and              the number of free disk quota entries.       /proc/sys/fs/epoll (since Linux 2.6.28)              This directory contains the file max_user_watches, which can              be used to limit the amount of kernel memory consumed by the              epoll interface.  For further details, see epoll(7).       /proc/sys/fs/file-max              This file defines a system-wide limit on the number of open              files for all processes.  (See also setrlimit(2), which can be              used by a process to set the per-process limit, RLIMIT_NOFILE,              on the number of files it may open.)  If you get lots of error              messages in the kernel log about running out of file handles              (look for "VFS: file-max limit <number> reached"), try              increasing this value:                  echo 100000 > /proc/sys/fs/file-max              Privileged processes (CAP_SYS_ADMIN) can override the file-max              limit.       /proc/sys/fs/file-nr              This (read-only) file contains three numbers: the number of              allocated file handles (i.e., the number of files presently              opened); the number of free file handles; and the maximum              number of file handles (i.e., the same value as              /proc/sys/fs/file-max).  If the number of allocated file              handles is close to the maximum, you should consider              increasing the maximum.  Before Linux 2.6, the kernel              allocated file handles dynamically, but it didn't free them              again.  Instead the free file handles were kept in a list for              reallocation; the "free file handles" value indicates the size              of that list.  A large number of free file handles indicates              that there was a past peak in the usage of open file handles.              Since Linux 2.6, the kernel does deallocate freed file              handles, and the "free file handles" value is always zero.       /proc/sys/fs/inode-max (only present until Linux 2.2)              This file contains the maximum number of in-memory inodes.              This value should be 3-4 times larger than the value in file-              max, since stdin, stdout and network sockets also need an              inode to handle them.  When you regularly run out of inodes,              you need to increase this value.              Starting with Linux 2.4, there is no longer a static limit on              the number of inodes, and this file is removed.       /proc/sys/fs/inode-nr              This file contains the first two values from inode-state.       /proc/sys/fs/inode-state              This file contains seven numbers: nr_inodes, nr_free_inodes,              preshrink, and four dummy values (always zero).              nr_inodes is the number of inodes the system has allocated.              nr_free_inodes represents the number of free inodes.              preshrink is nonzero when the nr_inodes > inode-max and the              system needs to prune the inode list instead of allocating              more; since Linux 2.4, this field is a dummy value (always              zero).       /proc/sys/fs/inotify (since Linux 2.6.13)              This directory contains files max_queued_events,              max_user_instances, and max_user_watches, that can be used to              limit the amount of kernel memory consumed by the inotify              interface.  For further details, see inotify(7).       /proc/sys/fs/lease-break-time              This file specifies the grace period that the kernel grants to              a process holding a file lease (fcntl(2)) after it has sent a              signal to that process notifying it that another process is              waiting to open the file.  If the lease holder does not remove              or downgrade the lease within this grace period, the kernel              forcibly breaks the lease.       /proc/sys/fs/leases-enable              This file can be used to enable or disable file leases              (fcntl(2)) on a system-wide basis.  If this file contains the              value 0, leases are disabled.  A nonzero value enables leases.       /proc/sys/fs/mqueue (since Linux 2.6.6)              This directory contains files msg_max, msgsize_max, and              queues_max, controlling the resources used by POSIX message              queues.  See mq_overview(7) for details.       /proc/sys/fs/nr_open (since Linux 2.6.25)              This file imposes ceiling on the value to which the              RLIMIT_NOFILE resource limit can be raised (see getrlimit(2)).              This ceiling is enforced for both unprivileged and privileged              process.  The default value in this file is 1048576.  (Before              Linux 2.6.25, the ceiling for RLIMIT_NOFILE was hard-coded to              the same value.)       /proc/sys/fs/overflowgid and /proc/sys/fs/overflowuid              These files allow you to change the value of the fixed UID and              GID.  The default is 65534.  Some filesystems support only              16-bit UIDs and GIDs, although in Linux UIDs and GIDs are 32              bits.  When one of these filesystems is mounted with writes              enabled, any UID or GID that would exceed 65535 is translated              to the overflow value before being written to disk.       /proc/sys/fs/pipe-max-size (since Linux 2.6.35)              The value in this file defines an upper limit for raising the              capacity of a pipe using the fcntl(2) F_SETPIPE_SZ operation.              This limit applies only to unprivileged processes.  The              default value for this file is 1,048,576.  The value assigned              to this file may be rounded upward, to reflect the value              actually employed for a convenient implementation.  To              determine the rounded-up value, display the contents of this              file after assigning a value to it.  The minimum value that              can be assigned to this file is the system page size.       /proc/sys/fs/protected_hardlinks (since Linux 3.6)              When the value in this file is 0, no restrictions are placed              on the creation of hard links (i.e., this is the historical              behavior before Linux 3.6).  When the value in this file is 1,              a hard link can be created to a target file only if one of the              following conditions is true:              *  The caller has the CAP_FOWNER capability.              *  The filesystem UID of the process creating the link matches                 the owner (UID) of the target file (as described in                 credentials(7), a process's filesystem UID is normally the                 same as its effective UID).              *  All of the following conditions are true:                  ·  the target is a regular file;                  ·  the target file does not have its set-user-ID                     permission bit enabled;                  ·  the target file does not have both its set-group-ID and                     group-executable permission bits enabled; and                  ·  the caller has permission to read and write the target                     file (either via the file's permissions mask or because                     it has suitable capabilities).              The default value in this file is 0.  Setting the value to 1              prevents a longstanding class of security issues caused by              hard-link-based time-of-check, time-of-use races, most              commonly seen in world-writable directories such as /tmp.  The              common method of exploiting this flaw is to cross privilege              boundaries when following a given hard link (i.e., a root              process follows a hard link created by another user).              Additionally, on systems without separated partitions, this              stops unauthorized users from "pinning" vulnerable set-user-ID              and set-group-ID files against being upgraded by the              administrator, or linking to special files.       /proc/sys/fs/protected_symlinks (since Linux 3.6)              When the value in this file is 0, no restrictions are placed              on following symbolic links (i.e., this is the historical              behavior before Linux 3.6).  When the value in this file is 1,              symbolic links are followed only in the following              circumstances:              *  the filesystem UID of the process following the link                 matches the owner (UID) of the symbolic link (as described                 in credentials(7), a process's filesystem UID is normally                 the same as its effective UID);              *  the link is not in a sticky world-writable directory; or              *  the symbolic link and its parent directory have the same                 owner (UID)              A system call that fails to follow a symbolic link because of              the above restrictions returns the error EACCES in errno.              The default value in this file is 0.  Setting the value to 1              avoids a longstanding class of security issues based on time-              of-check, time-of-use races when accessing symbolic links.       /proc/sys/fs/suid_dumpable (since Linux 2.6.13)              The value in this file is assigned to a process's "dumpable"              flag in the circumstances described in prctl(2).  In effect,              the value in this file determines whether core dump files are              produced for set-user-ID or otherwise protected/tainted              binaries.  Three different integer values can be specified:              0 (default)                     This provides the traditional (pre-Linux 2.6.13)                     behavior.  A core dump will not be produced for a                     process which has changed credentials (by calling                     seteuid(2), setgid(2), or similar, or by executing a                     set-user-ID or set-group-ID program) or whose binary                     does not have read permission enabled.              1 ("debug")                     All processes dump core when possible.  The core dump                     is owned by the filesystem user ID of the dumping                     process and no security is applied.  This is intended                     for system debugging situations only.  Ptrace is                     unchecked.              2 ("suidsafe")                     Any binary which normally would not be dumped (see "0"                     above) is dumped readable by root only.  This allows                     the user to remove the core dump file but not to read                     it.  For security reasons core dumps in this mode will                     not overwrite one another or other files.  This mode is                     appropriate when administrators are attempting to debug                     problems in a normal environment.                     Additionally, since Linux 3.6,                     /proc/sys/kernel/core_pattern must either be an                     absolute pathname or a pipe command, as detailed in                     core(5).  Warnings will be written to the kernel log if                     core_pattern does not follow these rules, and no core                     dump will be produced.       /proc/sys/fs/super-max              This file controls the maximum number of superblocks, and thus              the maximum number of mounted filesystems the kernel can have.              You need increase only super-max if you need to mount more              filesystems than the current value in super-max allows you to.       /proc/sys/fs/super-nr              This file contains the number of filesystems currently              mounted.       /proc/sys/kernel              This directory contains files controlling a range of kernel              parameters, as described below.       /proc/sys/kernel/acct              This file contains three numbers: highwater, lowwater, and              frequency.  If BSD-style process accounting is enabled, these              values control its behavior.  If free space on filesystem              where the log lives goes below lowwater percent, accounting              suspends.  If free space gets above highwater percent,              accounting resumes.  frequency determines how often the kernel              checks the amount of free space (value is in seconds).              Default values are 4, 2 and 30.  That is, suspend accounting              if 2% or less space is free; resume it if 4% or more space is              free; consider information about amount of free space valid              for 30 seconds.       /proc/sys/kernel/auto_msgmni (Linux 2.6.27 to 3.18)              From Linux 2.6.27 to 3.18, this file was used to control              recomputing of the value in /proc/sys/kernel/msgmni upon the              addition or removal of memory or upon IPC namespace              creation/removal.  Echoing "1" into this file enabled msgmni              automatic recomputing (and triggered a recomputation of msgmni              based on the current amount of available memory and number of              IPC namespaces).  Echoing "0" disabled automatic recomputing.              (Automatic recomputing was also disabled if a value was              explicitly assigned to /proc/sys/kernel/msgmni.)  The default              value in auto_msgmni was 1.              Since Linux 3.19, the content of this file has no effect              (because msgmni defaults to near the maximum value possible),              and reads from this file always return the value "0".       /proc/sys/kernel/cap_last_cap (since Linux 3.2)              See capabilities(7).       /proc/sys/kernel/cap-bound (from Linux 2.2 to 2.6.24)              This file holds the value of the kernel capability bounding              set (expressed as a signed decimal number).  This set is ANDed              against the capabilities permitted to a process during              execve(2).  Starting with Linux 2.6.25, the system-wide              capability bounding set disappeared, and was replaced by a              per-thread bounding set; see capabilities(7).       /proc/sys/kernel/core_pattern              See core(5).       /proc/sys/kernel/core_uses_pid              See core(5).       /proc/sys/kernel/ctrl-alt-del              This file controls the handling of Ctrl-Alt-Del from the              keyboard.  When the value in this file is 0, Ctrl-Alt-Del is              trapped and sent to the init(1) program to handle a graceful              restart.  When the value is greater than zero, Linux's              reaction to a Vulcan Nerve Pinch (tm) will be an immediate              reboot, without even syncing its dirty buffers.  Note: when a              program (like dosemu) has the keyboard in "raw" mode, the              ctrl-alt-del is intercepted by the program before it ever              reaches the kernel tty layer, and it's up to the program to              decide what to do with it.       /proc/sys/kernel/dmesg_restrict (since Linux 2.6.37)              The value in this file determines who can see kernel syslog              contents.  A value of 0 in this file imposes no restrictions.              If the value is 1, only privileged users can read the kernel              syslog.  (See syslog(2) for more details.)  Since Linux 3.4,              only users with the CAP_SYS_ADMIN capability may change the              value in this file.       /proc/sys/kernel/domainname and /proc/sys/kernel/hostname              can be used to set the NIS/YP domainname and the hostname of              your box in exactly the same way as the commands domainname(1)              and hostname(1), that is:                  # echo 'darkstar' > /proc/sys/kernel/hostname                  # echo 'mydomain' > /proc/sys/kernel/domainname              has the same effect as                  # hostname 'darkstar'                  # domainname 'mydomain'              Note, however, that the classic darkstar.frop.org has the              hostname "darkstar" and DNS (Internet Domain Name Server)              domainname "frop.org", not to be confused with the NIS              (Network Information Service) or YP (Yellow Pages) domainname.              These two domain names are in general different.  For a              detailed discussion see the hostname(1) man page.       /proc/sys/kernel/hotplug              This file contains the path for the hotplug policy agent.  The              default value in this file is /sbin/hotplug.       /proc/sys/kernel/htab-reclaim              (PowerPC only) If this file is set to a nonzero value, the              PowerPC htab (see kernel file              Documentation/powerpc/ppc_htab.txt) is pruned each time the              system hits the idle loop.       /proc/sys/kernel/kptr_restrict (since Linux 2.6.38)              The value in this file determines whether kernel addresses are              exposed via /proc files and other interfaces.  A value of 0 in              this file imposes no restrictions.  If the value is 1, kernel              pointers printed using the %pK format specifier will be              replaced with zeros unless the user has the CAP_SYSLOG              capability.  If the value is 2, kernel pointers printed using              the %pK format specifier will be replaced with zeros              regardless of the user's capabilities.  The initial default              value for this file was 1, but the default was changed to 0 in              Linux 2.6.39.  Since Linux 3.4, only users with the              CAP_SYS_ADMIN capability can change the value in this file.       /proc/sys/kernel/l2cr              (PowerPC only) This file contains a flag that controls the L2              cache of G3 processor boards.  If 0, the cache is disabled.              Enabled if nonzero.       /proc/sys/kernel/modprobe              This file contains the path for the kernel module loader.  The              default value is /sbin/modprobe.  The file is present only if              the kernel is built with the CONFIG_MODULES (CONFIG_KMOD in              Linux 2.6.26 and earlier) option enabled.  It is described by              the Linux kernel source file Documentation/kmod.txt (present              only in kernel 2.4 and earlier).       /proc/sys/kernel/modules_disabled (since Linux 2.6.31)              A toggle value indicating if modules are allowed to be loaded              in an otherwise modular kernel.  This toggle defaults to off              (0), but can be set true (1).  Once true, modules can be              neither loaded nor unloaded, and the toggle cannot be set back              to false.  The file is present only if the kernel is built              with the CONFIG_MODULES option enabled.       /proc/sys/kernel/msgmax (since Linux 2.2)              This file defines a system-wide limit specifying the maximum              number of bytes in a single message written on a System V              message queue.       /proc/sys/kernel/msgmni (since Linux 2.4)              This file defines the system-wide limit on the number of              message queue identifiers.  See also              /proc/sys/kernel/auto_msgmni.       /proc/sys/kernel/msgmnb (since Linux 2.2)              This file defines a system-wide parameter used to initialize              the msg_qbytes setting for subsequently created message              queues.  The msg_qbytes setting specifies the maximum number              of bytes that may be written to the message queue.       /proc/sys/kernel/ngroups_max (since Linux 2.6.4)              This is a read-only file that displays the upper limit on the              number of a process's group memberships.       /proc/sys/kernel/ostype and /proc/sys/kernel/osrelease              These files give substrings of /proc/version.       /proc/sys/kernel/overflowgid and /proc/sys/kernel/overflowuid              These files duplicate the files /proc/sys/fs/overflowgid and              /proc/sys/fs/overflowuid.       /proc/sys/kernel/panic              This file gives read/write access to the kernel variable              panic_timeout.  If this is zero, the kernel will loop on a              panic; if nonzero, it indicates that the kernel should              autoreboot after this number of seconds.  When you use the              software watchdog device driver, the recommended setting is              60.       /proc/sys/kernel/panic_on_oops (since Linux 2.5.68)              This file controls the kernel's behavior when an oops or BUG              is encountered.  If this file contains 0, then the system              tries to continue operation.  If it contains 1, then the              system delays a few seconds (to give klogd time to record the              oops output) and then panics.  If the /proc/sys/kernel/panic              file is also nonzero, then the machine will be rebooted.       /proc/sys/kernel/pid_max (since Linux 2.5.34)              This file specifies the value at which PIDs wrap around (i.e.,              the value in this file is one greater than the maximum PID).              PIDs greater than this value are not allocated; thus, the              value in this file also acts as a system-wide limit on the              total number of processes and threads.  The default value for              this file, 32768, results in the same range of PIDs as on              earlier kernels.  On 32-bit platforms, 32768 is the maximum              value for pid_max.  On 64-bit systems, pid_max can be set to              any value up to 2^22 (PID_MAX_LIMIT, approximately 4 million).       /proc/sys/kernel/powersave-nap (PowerPC only)              This file contains a flag.  If set, Linux-PPC will use the              "nap" mode of powersaving, otherwise the "doze" mode will be              used.       /proc/sys/kernel/printk              See syslog(2).       /proc/sys/kernel/pty (since Linux 2.6.4)              This directory contains two files relating to the number of              UNIX 98 pseudoterminals (see pts(4)) on the system.       /proc/sys/kernel/pty/max              This file defines the maximum number of pseudoterminals.       /proc/sys/kernel/pty/nr              This read-only file indicates how many pseudoterminals are              currently in use.       /proc/sys/kernel/random              This directory contains various parameters controlling the              operation of the file /dev/random.  See random(4) for further              information.       /proc/sys/kernel/random/uuid (since Linux 2.4)              Each read from this read-only file returns a randomly              generated 128-bit UUID, as a string in the standard UUID              format.       /proc/sys/kernel/randomize_va_space (since Linux 2.6.12)              Select the address space layout randomization (ASLR) policy              for the system (on architectures that support ASLR).  Three              values are supported for this file:              0  Turn ASLR off.  This is the default for architectures that                 don't support ASLR, and when the kernel is booted with the                 norandmaps parameter.              1  Make the addresses of mmap(2) allocations, the stack, and                 the VDSO page randomized.  Among other things, this means                 that shared libraries will be loaded at randomized                 addresses.  The text segment of PIE-linked binaries will                 also be loaded at a randomized address.  This value is the                 default if the kernel was configured with                 CONFIG_COMPAT_BRK.              2  (Since Linux 2.6.25) Also support heap randomization.  This                 value is the default if the kernel was not configured with                 CONFIG_COMPAT_BRK.       /proc/sys/kernel/real-root-dev              This file is documented in the Linux kernel source file              Documentation/initrd.txt.       /proc/sys/kernel/reboot-cmd (Sparc only)              This file seems to be a way to give an argument to the SPARC              ROM/Flash boot loader.  Maybe to tell it what to do after              rebooting?       /proc/sys/kernel/rtsig-max              (Only in kernels up to and including 2.6.7; see setrlimit(2))              This file can be used to tune the maximum number of POSIX              real-time (queued) signals that can be outstanding in the              system.       /proc/sys/kernel/rtsig-nr              (Only in kernels up to and including 2.6.7.)  This file shows              the number POSIX real-time signals currently queued.       /proc/sys/kernel/sched_rr_timeslice_ms (since Linux 3.9)              See sched_rr_get_interval(2).       /proc/sys/kernel/sched_rt_period_us (Since Linux 2.6.25)              See sched(7).       /proc/sys/kernel/sched_rt_runtime_us (Since Linux 2.6.25)              See sched(7).       /proc/sys/kernel/sem (since Linux 2.4)              This file contains 4 numbers defining limits for System V IPC              semaphores.  These fields are, in order:              SEMMSL  The maximum semaphores per semaphore set.              SEMMNS  A system-wide limit on the number of semaphores in all                      semaphore sets.              SEMOPM  The maximum number of operations that may be specified                      in a semop(2) call.              SEMMNI  A system-wide limit on the maximum number of semaphore                      identifiers.       /proc/sys/kernel/sg-big-buff              This file shows the size of the generic SCSI device (sg)              buffer.  You can't tune it just yet, but you could change it              at compile time by editing include/scsi/sg.h and changing the              value of SG_BIG_BUFF.  However, there shouldn't be any reason              to change this value.       /proc/sys/kernel/shm_rmid_forced (since Linux 3.1)              If this file is set to 1, all System V shared memory segments              will be marked for destruction as soon as the number of              attached processes falls to zero; in other words, it is no              longer possible to create shared memory segments that exist              independently of any attached process.              The effect is as though a shmctl(2) IPC_RMID is performed on              all existing segments as well as all segments created in the              future (until this file is reset to 0).  Note that existing              segments that are attached to no process will be immediately              destroyed when this file is set to 1.  Setting this option              will also destroy segments that were created, but never              attached, upon termination of the process that created the              segment with shmget(2).              Setting this file to 1 provides a way of ensuring that all              System V shared memory segments are counted against the              resource usage and resource limits (see the description of              RLIMIT_AS in getrlimit(2)) of at least one process.              Because setting this file to 1 produces behavior that is              nonstandard and could also break existing applications, the              default value in this file is 0.  Only set this file to 1 if              you have a good understanding of the semantics of the              applications using System V shared memory on your system.       /proc/sys/kernel/shmall (since Linux 2.2)              This file contains the system-wide limit on the total number              of pages of System V shared memory.       /proc/sys/kernel/shmmax (since Linux 2.2)              This file can be used to query and set the run-time limit on              the maximum (System V IPC) shared memory segment size that can              be created.  Shared memory segments up to 1GB are now              supported in the kernel.  This value defaults to SHMMAX.       /proc/sys/kernel/shmmni (since Linux 2.4)              This file specifies the system-wide maximum number of System V              shared memory segments that can be created.       /proc/sys/kernel/sysrq              This file controls the functions allowed to be invoked by the              SysRq key.  By default, the file contains 1 meaning that every              possible SysRq request is allowed (in older kernel versions,              SysRq was disabled by default, and you were required to              specifically enable it at run-time, but this is not the case              any more).  Possible values in this file are:                 0 - disable sysrq completely                 1 - enable all functions of sysrq                >1 - bit mask of allowed sysrq functions, as follows:                        2 - enable control of console logging level                        4 - enable control of keyboard (SAK, unraw)                        8 - enable debugging dumps of processes etc.                       16 - enable sync command                       32 - enable remount read-only                       64 - enable signaling of processes (term, kill, oom-              kill)                      128 - allow reboot/poweroff                      256 - allow nicing of all real-time tasks              This file is present only if the CONFIG_MAGIC_SYSRQ kernel              configuration option is enabled.  For further details see the              Linux kernel source file Documentation/sysrq.txt.       /proc/sys/kernel/version              This file contains a string like:                  #5 Wed Feb 25 21:49:24 MET 1998              The "#5" means that this is the fifth kernel built from this              source base and the date behind it indicates the time the              kernel was built.       /proc/sys/kernel/threads-max (since Linux 2.3.11)              This file specifies the system-wide limit on the number of              threads (tasks) that can be created on the system.       /proc/sys/kernel/zero-paged (PowerPC only)              This file contains a flag.  When enabled (nonzero), Linux-PPC              will pre-zero pages in the idle loop, possibly speeding up              get_free_pages.       /proc/sys/net              This directory contains networking stuff.  Explanations for              some of the files under this directory can be found in tcp(7)              and ip(7).       /proc/sys/net/core/somaxconn              This file defines a ceiling value for the backlog argument of              listen(2); see the listen(2) manual page for details.       /proc/sys/proc              This directory may be empty.       /proc/sys/sunrpc              This directory supports Sun remote procedure call for network              filesystem (NFS).  On some systems, it is not present.       /proc/sys/vm              This directory contains files for memory management tuning,              buffer and cache management.       /proc/sys/vm/compact_memory (since Linux 2.6.35)              When 1 is written to this file, all zones are compacted such              that free memory is available in contiguous blocks where              possible.  The effect of this action can be seen by examining              /proc/buddyinfo.              Only present if the kernel was configured with              CONFIG_COMPACTION.       /proc/sys/vm/drop_caches (since Linux 2.6.16)              Writing to this file causes the kernel to drop clean caches,              dentries, and inodes from memory, causing that memory to              become free.  This can be useful for memory management testing              and performing reproducible filesystem benchmarks.  Because              writing to this file causes the benefits of caching to be              lost, it can degrade overall system performance.              To free pagecache, use:                  echo 1 > /proc/sys/vm/drop_caches              To free dentries and inodes, use:                  echo 2 > /proc/sys/vm/drop_caches              To free pagecache, dentries and inodes, use:                  echo 3 > /proc/sys/vm/drop_caches              Because writing to this file is a nondestructive operation and              dirty objects are not freeable, the user should run sync(1)              first.       /proc/sys/vm/legacy_va_layout (since Linux 2.6.9)              If nonzero, this disables the new 32-bit memory-mapping              layout; the kernel will use the legacy (2.4) layout for all              processes.       /proc/sys/vm/memory_failure_early_kill (since Linux 2.6.32)              Control how to kill processes when an uncorrected memory error              (typically a 2-bit error in a memory module) that cannot be              handled by the kernel is detected in the background by              hardware.  In some cases (like the page still having a valid              copy on disk), the kernel will handle the failure              transparently without affecting any applications.  But if              there is no other up-to-date copy of the data, it will kill              processes to prevent any data corruptions from propagating.              The file has one of the following values:              1:  Kill all processes that have the corrupted-and-not-                  reloadable page mapped as soon as the corruption is                  detected.  Note this is not supported for a few types of                  pages, like kernel internally allocated data or the swap                  cache, but works for the majority of user pages.              0:  Only unmap the corrupted page from all processes and kill                  only a process that tries to access it.              The kill is performed using a SIGBUS signal with si_code set              to BUS_MCEERR_AO.  Processes can handle this if they want to;              see sigaction(2) for more details.              This feature is active only on architectures/platforms with              advanced machine check handling and depends on the hardware              capabilities.              Applications can override the memory_failure_early_kill              setting individually with the prctl(2) PR_MCE_KILL operation.              Only present if the kernel was configured with              CONFIG_MEMORY_FAILURE.       /proc/sys/vm/memory_failure_recovery (since Linux 2.6.32)              Enable memory failure recovery (when supported by the              platform)              1:  Attempt recovery.              0:  Always panic on a memory failure.              Only present if the kernel was configured with              CONFIG_MEMORY_FAILURE.       /proc/sys/vm/oom_dump_tasks (since Linux 2.6.25)              Enables a system-wide task dump (excluding kernel threads) to              be produced when the kernel performs an OOM-killing.  The dump              includes the following information for each task (thread,              process): thread ID, real user ID, thread group ID (process              ID), virtual memory size, resident set size, the CPU that the              task is scheduled on, oom_adj score (see the description of              /proc/[pid]/oom_adj), and command name.  This is helpful to              determine why the OOM-killer was invoked and to identify the              rogue task that caused it.              If this contains the value zero, this information is              suppressed.  On very large systems with thousands of tasks, it              may not be feasible to dump the memory state information for              each one.  Such systems should not be forced to incur a              performance penalty in OOM situations when the information may              not be desired.              If this is set to nonzero, this information is shown whenever              the OOM-killer actually kills a memory-hogging task.              The default value is 0.       /proc/sys/vm/oom_kill_allocating_task (since Linux 2.6.24)              This enables or disables killing the OOM-triggering task in              out-of-memory situations.              If this is set to zero, the OOM-killer will scan through the              entire tasklist and select a task based on heuristics to kill.              This normally selects a rogue memory-hogging task that frees              up a large amount of memory when killed.              If this is set to nonzero, the OOM-killer simply kills the              task that triggered the out-of-memory condition.  This avoids              a possibly expensive tasklist scan.              If /proc/sys/vm/panic_on_oom is nonzero, it takes precedence              over whatever value is used in              /proc/sys/vm/oom_kill_allocating_task.              The default value is 0.       /proc/sys/vm/overcommit_kbytes (since Linux 3.14)              This writable file provides an alternative to              /proc/sys/vm/overcommit_ratio for controlling the CommitLimit              when /proc/sys/vm/overcommit_memory has the value 2.  It              allows the amount of memory overcommitting to be specified as              an absolute value (in kB), rather than as a percentage, as is              done with overcommit_ratio.  This allows for finer-grained              control of CommitLimit on systems with extremely large memory              sizes.              Only one of overcommit_kbytes or overcommit_ratio can have an              effect: if overcommit_kbytes has a nonzero value, then it is              used to calculate CommitLimit, otherwise overcommit_ratio is              used.  Writing a value to either of these files causes the              value in the other file to be set to zero.       /proc/sys/vm/overcommit_memory              This file contains the kernel virtual memory accounting mode.              Values are:                     0: heuristic overcommit (this is the default)                     1: always overcommit, never check                     2: always check, never overcommit              In mode 0, calls of mmap(2) with MAP_NORESERVE are not              checked, and the default check is very weak, leading to the              risk of getting a process "OOM-killed".  Under Linux 2.4, any              nonzero value implies mode 1.              In mode 2 (available since Linux 2.6), the total virtual              address space that can be allocated (CommitLimit in              /proc/meminfo) is calculated as                  CommitLimit = (total_RAM - total_huge_TLB) *                                overcommit_ratio / 100 + total_swap              where:                   *  total_RAM is the total amount of RAM on the system;                   *  total_huge_TLB is the amount of memory set aside for                      huge pages;                   *  overcommit_ratio is the value in                      /proc/sys/vm/overcommit_ratio; and                   *  total_swap is the amount of swap space.              For example, on a system with 16GB of physical RAM, 16GB of              swap, no space dedicated to huge pages, and an              overcommit_ratio of 50, this formula yields a CommitLimit of              24GB.              Since Linux 3.14, if the value in              /proc/sys/vm/overcommit_kbytes is nonzero, then CommitLimit is              instead calculated as:                  CommitLimit = overcommit_kbytes + total_swap       /proc/sys/vm/overcommit_ratio (since Linux 2.6.0)              This writable file defines a percentage by which memory can be              overcommitted.  The default value in the file is 50.  See the              description of /proc/sys/vm/overcommit_memory.       /proc/sys/vm/panic_on_oom (since Linux 2.6.18)              This enables or disables a kernel panic in an out-of-memory              situation.              If this file is set to the value 0, the kernel's OOM-killer              will kill some rogue process.  Usually, the OOM-killer is able              to kill a rogue process and the system will survive.              If this file is set to the value 1, then the kernel normally              panics when out-of-memory happens.  However, if a process              limits allocations to certain nodes using memory policies              (mbind(2) MPOL_BIND) or cpusets (cpuset(7)) and those nodes              reach memory exhaustion status, one process may be killed by              the OOM-killer.  No panic occurs in this case: because other              nodes' memory may be free, this means the system as a whole              may not have reached an out-of-memory situation yet.              If this file is set to the value 2, the kernel always panics              when an out-of-memory condition occurs.              The default value is 0.  1 and 2 are for failover of              clustering.  Select either according to your policy of              failover.       /proc/sys/vm/swappiness              The value in this file controls how aggressively the kernel              will swap memory pages.  Higher values increase              aggressiveness, lower values decrease aggressiveness.  The              default value is 60.       /proc/sysrq-trigger (since Linux 2.4.21)              Writing a character to this file triggers the same SysRq              function as typing ALT-SysRq-<character> (see the description              of /proc/sys/kernel/sysrq).  This file is normally writable              only by root.  For further details see the Linux kernel source              file Documentation/sysrq.txt.       /proc/sysvipc              Subdirectory containing the pseudo-files msg, sem and shm.              These files list the System V Interprocess Communication (IPC)              objects (respectively: message queues, semaphores, and shared              memory) that currently exist on the system, providing similar              information to that available via ipcs(1).  These files have              headers and are formatted (one IPC object per line) for easy              understanding.  svipc(7) provides further background on the              information shown by these files.       /proc/thread-self (since Linux 3.17)              This directory refers to the thread accessing the /proc              filesystem, and is identical to the /proc/self/task/[tid]              directory named by the process thread ID ([tid]) of the same              thread.       /proc/timer_list (since Linux 2.6.21)              This read-only file exposes a list of all currently pending              (high-resolution) timers, all clock-event sources, and their              parameters in a human-readable form.       /proc/timer_stats (since Linux 2.6.21)              This is a debugging facility to make timer (ab)use in a Linux              system visible to kernel and user-space developers.  It can be              used by kernel and user-space developers to verify that their              code does not make undue use of timers.  The goal is to avoid              unnecessary wakeups, thereby optimizing power consumption.              If enabled in the kernel (CONFIG_TIMER_STATS), but not used,              it has almost zero runtime overhead and a relatively small              data-structure overhead.  Even if collection is enabled at              runtime, overhead is low: all the locking is per-CPU and              lookup is hashed.              The /proc/timer_stats file is used both to control sampling              facility and to read out the sampled information.              The timer_stats functionality is inactive on bootup.  A              sampling period can be started using the following command:                  # echo 1 > /proc/timer_stats              The following command stops a sampling period:                  # echo 0 > /proc/timer_stats              The statistics can be retrieved by:                  $ cat /proc/timer_stats              While sampling is enabled, each readout from /proc/timer_stats              will see newly updated statistics.  Once sampling is disabled,              the sampled information is kept until a new sample period is              started.  This allows multiple readouts.              Sample output from /proc/timer_stats:   $ cat /proc/timer_stats   Timer Stats Version: v0.3   Sample period: 1.764 s   Collection: active     255,     0 swapper/3        hrtimer_start_range_ns (tick_sched_timer)      71,     0 swapper/1        hrtimer_start_range_ns (tick_sched_timer)      58,     0 swapper/0        hrtimer_start_range_ns (tick_sched_timer)       4,  1694 gnome-shell      mod_delayed_work_on (delayed_work_timer_fn)      17,     7 rcu_sched        rcu_gp_kthread (process_timeout)   ...       1,  4911 kworker/u16:0    mod_delayed_work_on (delayed_work_timer_fn)      1D,  2522 kworker/0:0      queue_delayed_work_on (delayed_work_timer_fn)   1029 total events, 583.333 events/sec              The output columns are:              *  a count of the number of events, optionally (since Linux                 2.6.23) followed by the letter 'D' if this is a deferrable                 timer;              *  the PID of the process that initialized the timer;              *  the name of the process that initialized the timer;              *  the function where the timer was initialized; and              *  (in parentheses) the callback function that is associated                 with the timer.       /proc/tty              Subdirectory containing the pseudo-files and subdirectories              for tty drivers and line disciplines.       /proc/uptime              This file contains two numbers: the uptime of the system              (seconds), and the amount of time spent in idle process              (seconds).       /proc/version              This string identifies the kernel version that is currently              running.  It includes the contents of /proc/sys/kernel/ostype,              /proc/sys/kernel/osrelease and /proc/sys/kernel/version.  For              example:            Linux version 1.0.9 (quinlan@phaze) #1 Sat May 14 01:51:54 EDT 1994       /proc/vmstat (since Linux 2.6)              This file displays various virtual memory statistics.       /proc/zoneinfo (since Linux 2.6.13)              This file display information about memory zones.  This is              useful for analyzing virtual memory behavior.

NOTES         top

       Many strings (i.e., the environment and command line) are in the       internal format, with subfields terminated by null bytes ('\0'), so       you may find that things are more readable if you use od -c or tr       "\000" "\n" to read them.  Alternatively, echo `cat <file>` works       well.       This manual page is incomplete, possibly inaccurate, and is the kind       of thing that needs to be updated very often.

SEE ALSO         top

       cat(1), dmesg(1), find(1), free(1), ps(1), tr(1), uptime(1),       chroot(2), mmap(2), readlink(2), syslog(2), slabinfo(5), hier(7),       namespaces(7), time(7), arp(8), hdparm(8), ifconfig(8), init(1),       lsmod(8), lspci(8), mount(8), netstat(8), procinfo(8), route(8),       sysctl(8)       The Linux kernel source files: Documentation/filesystems/proc.txt       Documentation/sysctl/fs.txt, Documentation/sysctl/kernel.txt,       Documentation/sysctl/net.txt, and Documentation/sysctl/vm.txt.

COLOPHON         top

       This page is part of release 3.83 of the Linux man-pages project.  A       description of the project, information about reporting bugs, and the       latest version of this page, can be found at       http://www.kernel.org/doc/man-pages/.Linux                            2015-03-29                          PROC(5)

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