linux文件监控(网站拷贝英文仅转存浏览)
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NAME | DESCRIPTION | VERSIONS | CONFORMING TO | NOTES | BUGS | EXAMPLE | SEE ALSO | COLOPHON
INOTIFY(7) Linux Programmer's Manual INOTIFY(7)
NAME top
inotify - monitoring filesystem events
DESCRIPTION top
The inotify API provides a mechanism for monitoring filesystem events. Inotify can be used to monitor individual files, or to monitor directories. When a directory is monitored, inotify will return events for the directory itself, and for files inside the directory. The following system calls are used with this API: * inotify_init(2) creates an inotify instance and returns a file descriptor referring to the inotify instance. The more recent inotify_init1(2) is like inotify_init(2), but has a flags argument that provides access to some extra functionality. * inotify_add_watch(2) manipulates the "watch list" associated with an inotify instance. Each item ("watch") in the watch list specifies the pathname of a file or directory, along with some set of events that the kernel should monitor for the file referred to by that pathname. inotify_add_watch(2) either creates a new watch item, or modifies an existing watch. Each watch has a unique "watch descriptor", an integer returned by inotify_add_watch(2) when the watch is created. * When events occur for monitored files and directories, those events are made available to the application as structured data that can be read from the inotify file descriptor using read(2) (see below). * inotify_rm_watch(2) removes an item from an inotify watch list. * When all file descriptors referring to an inotify instance have been closed (using close(2)), the underlying object and its resources are freed for reuse by the kernel; all associated watches are automatically freed. With careful programming, an application can use inotify to efficiently monitor and cache the state of a set of filesystem objects. However, robust applications should allow for the fact that bugs in the monitoring logic or races of the kind described below may leave the cache inconsistent with the filesystem state. It is probably wise to to do some consistency checking, and rebuild the cache when inconsistencies are detected. Reading events from an inotify file descriptor To determine what events have occurred, an application read(2)s from the inotify file descriptor. If no events have so far occurred, then, assuming a blocking file descriptor, read(2) will block until at least one event occurs (unless interrupted by a signal, in which case the call fails with the error EINTR; see signal(7)). Each successful read(2) returns a buffer containing one or more of the following structures: struct inotify_event { int wd; /* Watch descriptor */ uint32_t mask; /* Mask of events */ uint32_t cookie; /* Unique cookie associating related events (for rename(2)) */ uint32_t len; /* Size of name field */ char name[]; /* Optional null-terminated name */ }; wd identifies the watch for which this event occurs. It is one of the watch descriptors returned by a previous call to inotify_add_watch(2). mask contains bits that describe the event that occurred (see below). cookie is a unique integer that connects related events. Currently this is used only for rename events, and allows the resulting pair of IN_MOVED_FROM and IN_MOVED_TO events to be connected by the application. For all other event types, cookie is set to 0. The name field is present only when an event is returned for a file inside a watched directory; it identifies the file pathname relative to the watched directory. This pathname is null-terminated, and may include further null bytes ('\0') to align subsequent reads to a suitable address boundary. The len field counts all of the bytes in name, including the null bytes; the length of each inotify_event structure is thus sizeof(struct inotify_event)+len. The behavior when the buffer given to read(2) is too small to return information about the next event depends on the kernel version: in kernels before 2.6.21, read(2) returns 0; since kernel 2.6.21, read(2) fails with the error EINVAL. Specifying a buffer of size sizeof(struct inotify_event) + NAME_MAX + 1 will be sufficient to read at least one event. inotify events The inotify_add_watch(2) mask argument and the mask field of the inotify_event structure returned when read(2)ing an inotify file descriptor are both bit masks identifying inotify events. The following bits can be specified in mask when calling inotify_add_watch(2) and may be returned in the mask field returned by read(2): IN_ACCESS (*) File was accessed (e.g., read(2), execve(2)). IN_ATTRIB (*) Metadata changed—for example, permissions (e.g., chmod(2)), timestamps (e.g., utimensat(2)), extended attributes (setxattr(2)), link count (since Linux 2.6.25; e.g., for the target of link(2) and for unlink(2)), and user/group ID (e.g., chown(2)). IN_CLOSE_WRITE (*) File opened for writing was closed. IN_CLOSE_NOWRITE (*) File not opened for writing was closed. IN_CREATE (*) File/directory created in watched directory (e.g., open(2) O_CREAT, mkdir(2), link(2), symlink(2), bind(2) on a UNIX domain socket). IN_DELETE (*) File/directory deleted from watched directory. IN_DELETE_SELF Watched file/directory was itself deleted. (This event also occurs if an object is moved to another filesystem, since mv(1) in effect copies the file to the other filesystem and then deletes it from the original filesystem.) In addition, an IN_IGNORED event will subsequently be generated for the watch descriptor. IN_MODIFY (*) File was modified (e.g., write(2), truncate(2)). IN_MOVE_SELF Watched file/directory was itself moved. IN_MOVED_FROM (*) Generated for the directory containing the old filename when a file is renamed. IN_MOVED_TO (*) Generated for the directory containing the new filename when a file is renamed. IN_OPEN (*) File was opened. When monitoring a directory, the events marked with an asterisk (*) above can occur for files in the directory, in which case the name field in the returned inotify_event structure identifies the name of the file within the directory. The IN_ALL_EVENTS macro is defined as a bit mask of all of the above events. This macro can be used as the mask argument when calling inotify_add_watch(2). Two additional convenience macros are defined: IN_MOVE Equates to IN_MOVED_FROM | IN_MOVED_TO. IN_CLOSE Equates to IN_CLOSE_WRITE | IN_CLOSE_NOWRITE. The following further bits can be specified in mask when calling inotify_add_watch(2): IN_DONT_FOLLOW (since Linux 2.6.15) Don't dereference pathname if it is a symbolic link. IN_EXCL_UNLINK (since Linux 2.6.36) By default, when watching events on the children of a directory, events are generated for children even after they have been unlinked from the directory. This can result in large numbers of uninteresting events for some applications (e.g., if watching /tmp, in which many applications create temporary files whose names are immediately unlinked). Specifying IN_EXCL_UNLINK changes the default behavior, so that events are not generated for children after they have been unlinked from the watched directory. IN_MASK_ADD Add (OR) events to watch mask for this pathname if it already exists (instead of replacing mask). IN_ONESHOT Monitor pathname for one event, then remove from watch list. IN_ONLYDIR (since Linux 2.6.15) Only watch pathname if it is a directory. The following bits may be set in the mask field returned by read(2): IN_IGNORED Watch was removed explicitly (inotify_rm_watch(2)) or automatically (file was deleted, or filesystem was unmounted). See also BUGS. IN_ISDIR Subject of this event is a directory. IN_Q_OVERFLOW Event queue overflowed (wd is -1 for this event). IN_UNMOUNT Filesystem containing watched object was unmounted. In addition, an IN_IGNORED event will subsequently be generated for the watch descriptor. Examples Suppose an application is watching the directory dir and the file dir/myfile for all events. The examples below show some events that will be generated for these two objects. fd = open("dir/myfile", O_RDWR); Generates IN_OPEN events for both dir and dir/myfile. read(fd, buf, count); Generates IN_ACCESS events for both dir and dir/myfile. write(fd, buf, count); Generates IN_MODIFY events for both dir and dir/myfile. fchmod(fd, mode); Generates IN_ATTRIB events for both dir and dir/myfile. close(fd); Generates IN_CLOSE_WRITE events for both dir and dir/myfile. Suppose an application is watching the directories dir1 and dir2, and the file dir1/myfile. The following examples show some events that may be generated. link("dir1/myfile", "dir2/new"); Generates an IN_ATTRIB event for myfile and an IN_CREATE event for dir2. rename("dir1/myfile", "dir2/myfile"); Generates an IN_MOVED_FROM event for dir1, an IN_MOVED_TO event for dir2, and an IN_MOVE_SELF event for myfile. The IN_MOVED_FROM and IN_MOVED_TO events will have the same cookie value. Suppose that dir1/xx and dir2/yy are (the only) links to the same file, and an application is watching dir1, dir2, dir1/xx, and dir2/yy. Executing the following calls in the order given below will generate the following events: unlink("dir2/yy"); Generates an IN_ATTRIB event for xx (because its link count changes) and an IN_DELETE event for dir2. unlink("dir1/xx"); Generates IN_ATTRIB, IN_DELETE_SELF, and IN_IGNORED events for xx, and an IN_DELETE event for dir1. Suppose an application is watching the directory dir and (the empty) directory dir/subdir. The following examples show some events that may be generated. mkdir("dir/new", mode); Generates an IN_CREATE | IN_ISDIR event for dir. rmdir("dir/subdir"); Generates IN_DELETE_SELF and IN_IGNORED events for subdir, and an IN_DELETE | IN_ISDIR event for dir. /proc interfaces The following interfaces can be used to limit the amount of kernel memory consumed by inotify: /proc/sys/fs/inotify/max_queued_events The value in this file is used when an application calls inotify_init(2) to set an upper limit on the number of events that can be queued to the corresponding inotify instance. Events in excess of this limit are dropped, but an IN_Q_OVERFLOW event is always generated. /proc/sys/fs/inotify/max_user_instances This specifies an upper limit on the number of inotify instances that can be created per real user ID. /proc/sys/fs/inotify/max_user_watches This specifies an upper limit on the number of watches that can be created per real user ID.
VERSIONS top
Inotify was merged into the 2.6.13 Linux kernel. The required library interfaces were added to glibc in version 2.4. (IN_DONT_FOLLOW, IN_MASK_ADD, and IN_ONLYDIR were added in glibc version 2.5.)
CONFORMING TO top
The inotify API is Linux-specific.
NOTES top
Inotify file descriptors can be monitored using select(2), poll(2), and epoll(7). When an event is available, the file descriptor indicates as readable. Since Linux 2.6.25, signal-driven I/O notification is available for inotify file descriptors; see the discussion of F_SETFL (for setting the O_ASYNC flag), F_SETOWN, and F_SETSIG in fcntl(2). The siginfo_t structure (described in sigaction(2)) that is passed to the signal handler has the following fields set: si_fd is set to the inotify file descriptor number; si_signo is set to the signal number; si_code is set to POLL_IN; and POLLIN is set in si_band. If successive output inotify events produced on the inotify file descriptor are identical (same wd, mask, cookie, and name), then they are coalesced into a single event if the older event has not yet been read (but see BUGS). This reduces the amount of kernel memory required for the event queue, but also means that an application can't use inotify to reliably count file events. The events returned by reading from an inotify file descriptor form an ordered queue. Thus, for example, it is guaranteed that when renaming from one directory to another, events will be produced in the correct order on the inotify file descriptor. The FIONREAD ioctl(2) returns the number of bytes available to read from an inotify file descriptor. Limitations and caveats The inotify API provides no information about the user or process that triggered the inotify event. In particular, there is no easy way for a process that is monitoring events via inotify to distinguish events that it triggers itself from those that are triggered by other processes. Inotify reports only events that a user-space program triggers through the filesystem API. As a result, it does not catch remote events that occur on network filesystems. (Applications must fall back to polling the filesystem to catch such events.) Furthermore, various pseudo-filesystems such as /proc, /sys, and /dev/pts are not monitorable with inotify. The inotify API does not report file accesses and modifications that may occur because of mmap(2), msync(2), and munmap(2). The inotify API identifies affected files by filename. However, by the time an application processes an inotify event, the filename may already have been deleted or renamed. The inotify API identifies events via watch descriptors. It is the application's responsibility to cache a mapping (if one is needed) between watch descriptors and pathnames. Be aware that directory renamings may affect multiple cached pathnames. Inotify monitoring of directories is not recursive: to monitor subdirectories under a directory, additional watches must be created. This can take a significant amount time for large directory trees. If monitoring an entire directory subtree, and a new subdirectory is created in that tree or an existing directory is renamed into that tree, be aware that by the time you create a watch for the new subdirectory, new files (and subdirectories) may already exist inside the subdirectory. Therefore, you may want to scan the contents of the subdirectory immediately after adding the watch (and, if desired, recursively add watches for any subdirectories that it contains). Note that the event queue can overflow. In this case, events are lost. Robust applications should handle the possibility of lost events gracefully. For example, it may be necessary to rebuild part or all of the application cache. (One simple, but possibly expensive, approach is to close the inotify file descriptor, empty the cache, create a new inotify file descriptor, and then re-create watches and cache entries for the objects to be monitored.) Dealing with rename() events As noted above, the IN_MOVED_FROM and IN_MOVED_TO event pair that is generated by rename(2) can be matched up via their shared cookie value. However, the task of matching has some challenges. These two events are usually consecutive in the event stream available when reading from the inotify file descriptor. However, this is not guaranteed. If multiple processes are triggering events for monitored objects, then (on rare occasions) an arbitrary number of other events may appear between the IN_MOVED_FROM and IN_MOVED_TO events. Matching up the IN_MOVED_FROM and IN_MOVED_TO event pair generated by rename(2) is thus inherently racy. (Don't forget that if an object is renamed outside of a monitored directory, there may not even be an IN_MOVED_TO event.) Heuristic approaches (e.g., assume the events are always consecutive) can be used to ensure a match in most cases, but will inevitably miss some cases, causing the application to perceive the IN_MOVED_FROM and IN_MOVED_TO events as being unrelated. If watch descriptors are destroyed and re-created as a result, then those watch descriptors will be inconsistent with the watch descriptors in any pending events. (Re-creating the inotify file descriptor and rebuilding the cache may be useful to deal with this scenario.) Applications should also allow for the possibility that the IN_MOVED_FROM event was the last event that could fit in the buffer returned by the current call to read(2), and the accompanying IN_MOVED_TO event might be fetched only on the next read(2).
BUGS top
In kernels before 2.6.16, the IN_ONESHOT mask flag does not work. As originally designed and implemented, the IN_ONESHOT flag did not cause an IN_IGNORED event to be generated when the watch was dropped after one event. However, as an unintended effect of other changes, since Linux 2.6.36, an IN_IGNORED event is generated in this case. Before kernel 2.6.25, the kernel code that was intended to coalesce successive identical events (i.e., the two most recent events could potentially be coalesced if the older had not yet been read) instead checked if the most recent event could be coalesced with the oldest unread event.
EXAMPLE top
The following program demonstrates the usage of the inotify API. It marks the directories passed as a command-line arguments and waits for events of type IN_OPEN, IN_CLOSE_NOWRITE and IN_CLOSE_WRITE. The following output was recorded while editing the file /home/user/temp/foo and listing directory /tmp. Before the file and the directory were opened, IN_OPEN events occurred. After the file was closed, an IN_CLOSE_WRITE event occurred. After the directory was closed, an IN_CLOSE_NOWRITE event occurred. Execution of the program ended when the user pressed the ENTER key. Example output $ ./a.out /tmp /home/user/temp Press enter key to terminate. Listening for events. IN_OPEN: /home/user/temp/foo [file] IN_CLOSE_WRITE: /home/user/temp/foo [file] IN_OPEN: /tmp/ [directory] IN_CLOSE_NOWRITE: /tmp/ [directory] Listening for events stopped. Program source #include <errno.h> #include <poll.h> #include <stdio.h> #include <stdlib.h> #include <sys/inotify.h> #include <unistd.h> /* Read all available inotify events from the file descriptor 'fd'. wd is the table of watch descriptors for the directories in argv. argc is the length of wd and argv. argv is the list of watched directories. Entry 0 of wd and argv is unused. */ static void handle_events(int fd, int *wd, int argc, char* argv[]) { /* Some systems cannot read integer variables if they are not properly aligned. On other systems, incorrect alignment may decrease performance. Hence, the buffer used for reading from the inotify file descriptor should have the same alignment as struct inotify_event. */ char buf[4096] __attribute__ ((aligned(__alignof__(struct inotify_event)))); const struct inotify_event *event; int i; ssize_t len; char *ptr; /* Loop while events can be read from inotify file descriptor. */ for (;;) { /* Read some events. */ len = read(fd, buf, sizeof buf); if (len == -1 && errno != EAGAIN) { perror("read"); exit(EXIT_FAILURE); } /* If the nonblocking read() found no events to read, then it returns -1 with errno set to EAGAIN. In that case, we exit the loop. */ if (len <= 0) break; /* Loop over all events in the buffer */ for (ptr = buf; ptr < buf + len; ptr += sizeof(struct inotify_event) + event->len) { event = (const struct inotify_event *) ptr; /* Print event type */ if (event->mask & IN_OPEN) printf("IN_OPEN: "); if (event->mask & IN_CLOSE_NOWRITE) printf("IN_CLOSE_NOWRITE: "); if (event->mask & IN_CLOSE_WRITE) printf("IN_CLOSE_WRITE: "); /* Print the name of the watched directory */ for (i = 1; i < argc; ++i) { if (wd[i] == event->wd) { printf("%s/", argv[i]); break; } } /* Print the name of the file */ if (event->len) printf("%s", event->name); /* Print type of filesystem object */ if (event->mask & IN_ISDIR) printf(" [directory]\n"); else printf(" [file]\n"); } } } int main(int argc, char* argv[]) { char buf; int fd, i, poll_num; int *wd; nfds_t nfds; struct pollfd fds[2]; if (argc < 2) { printf("Usage: %s PATH [PATH ...]\n", argv[0]); exit(EXIT_FAILURE); } printf("Press ENTER key to terminate.\n"); /* Create the file descriptor for accessing the inotify API */ fd = inotify_init1(IN_NONBLOCK); if (fd == -1) { perror("inotify_init1"); exit(EXIT_FAILURE); } /* Allocate memory for watch descriptors */ wd = calloc(argc, sizeof(int)); if (wd == NULL) { perror("calloc"); exit(EXIT_FAILURE); } /* Mark directories for events - file was opened - file was closed */ for (i = 1; i < argc; i++) { wd[i] = inotify_add_watch(fd, argv[i], IN_OPEN | IN_CLOSE); if (wd[i] == -1) { fprintf(stderr, "Cannot watch '%s'\n", argv[i]); perror("inotify_add_watch"); exit(EXIT_FAILURE); } } /* Prepare for polling */ nfds = 2; /* Console input */ fds[0].fd = STDIN_FILENO; fds[0].events = POLLIN; /* Inotify input */ fds[1].fd = fd; fds[1].events = POLLIN; /* Wait for events and/or terminal input */ printf("Listening for events.\n"); while (1) { poll_num = poll(fds, nfds, -1); if (poll_num == -1) { if (errno == EINTR) continue; perror("poll"); exit(EXIT_FAILURE); } if (poll_num > 0) { if (fds[0].revents & POLLIN) { /* Console input is available. Empty stdin and quit */ while (read(STDIN_FILENO, &buf, 1) > 0 && buf != '\n') continue; break; } if (fds[1].revents & POLLIN) { /* Inotify events are available */ handle_events(fd, wd, argc, argv); } } } printf("Listening for events stopped.\n"); /* Close inotify file descriptor */ close(fd); free(wd); exit(EXIT_SUCCESS); }
SEE ALSO top
inotifywait(1), inotifywatch(1), inotify_add_watch(2), inotify_init(2), inotify_init1(2), inotify_rm_watch(2), read(2), stat(2), fanotify(7) Documentation/filesystems/inotify.txt in the Linux kernel source tree
COLOPHON top
This page is part of release 3.69 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 2014-05-23 INOTIFY(7)
Copyright and license for this manual page
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | CONFORMING TO | SEE ALSO | COLOPHON
INOTIFY_ADD_WATCH(2) Linux Programmer's Manual INOTIFY_ADD_WATCH(2)
NAME top
inotify_add_watch - add a watch to an initialized inotify instance
SYNOPSIS top
#include <sys/inotify.h> int inotify_add_watch(int fd, const char *pathname, uint32_t mask);
DESCRIPTION top
inotify_add_watch() adds a new watch, or modifies an existing watch, for the file whose location is specified in pathname; the caller must have read permission for this file. The fd argument is a file descriptor referring to the inotify instance whose watch list is to be modified. The events to be monitored for pathname are specified in the mask bit-mask argument. See inotify(7) for a description of the bits that can be set in mask. A successful call to inotify_add_watch() returns the unique watch descriptor associated with pathname for this inotify instance. If pathname was not previously being watched by this inotify instance, then the watch descriptor is newly allocated. If pathname was already being watched, then the descriptor for the existing watch is returned. The watch descriptor is returned by later read(2)s from the inotify file descriptor. These reads fetch inotify_event structures (see inotify(7)) indicating filesystem events; the watch descriptor inside this structure identifies the object for which the event occurred.
RETURN VALUE top
On success, inotify_add_watch() returns a nonnegative watch descriptor. On error, -1 is returned and errno is set appropriately.
ERRORS top
EACCES Read access to the given file is not permitted. EBADF The given file descriptor is not valid. EFAULT pathname points outside of the process's accessible address space. EINVAL The given event mask contains no valid events; or fd is not an inotify file descriptor. ENAMETOOLONG pathname is too long. ENOENT A directory component in pathname does not exist or is a dangling symbolic link. ENOMEM Insufficient kernel memory was available. ENOSPC The user limit on the total number of inotify watches was reached or the kernel failed to allocate a needed resource.
VERSIONS top
Inotify was merged into the 2.6.13 Linux kernel.
CONFORMING TO top
This system call is Linux-specific.
SEE ALSO top
inotify_init(2), inotify_rm_watch(2), inotify(7)
COLOPHON top
This page is part of release 3.69 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 2014-03-28 INOTIFY_ADD_WATCH(2)
INOTIFY_INIT(2) Linux Programmer's Manual INOTIFY_INIT(2)
NAME top
inotify_init, inotify_init1 - initialize an inotify instance
SYNOPSIS top
#include <sys/inotify.h> int inotify_init(void); int inotify_init1(int flags);
DESCRIPTION top
For an overview of the inotify API, see inotify(7). inotify_init() initializes a new inotify instance and returns a file descriptor associated with a new inotify event queue. If flags is 0, then inotify_init1() is the same as inotify_init(). The following values can be bitwise ORed in flags to obtain different behavior: IN_NONBLOCK Set the O_NONBLOCK file status flag on the new open file description. Using this flag saves extra calls to fcntl(2) to achieve the same result. IN_CLOEXEC Set the close-on-exec (FD_CLOEXEC) flag on the new file descriptor. See the description of the O_CLOEXEC flag in open(2) for reasons why this may be useful.
RETURN VALUE top
On success, these system calls return a new file descriptor. On error, -1 is returned, and errno is set to indicate the error.
ERRORS top
EINVAL (inotify_init1()) An invalid value was specified in flags. EMFILE The user limit on the total number of inotify instances has been reached. ENFILE The system limit on the total number of file descriptors has been reached. ENOMEM Insufficient kernel memory is available.
VERSIONS top
inotify_init() first appeared in Linux 2.6.13; library support was added to glibc in version 2.4. inotify_init1() was added in Linux 2.6.27; library support was added to glibc in version 2.9.
CONFORMING TO top
These system calls are Linux-specific.
SEE ALSO top
inotify_add_watch(2), inotify_rm_watch(2), inotify(7)
COLOPHON top
This page is part of release 3.69 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 2014-03-28 INOTIFY_INIT(2)
INOTIFY_RM_WATCH(2) Linux Programmer's Manual INOTIFY_RM_WATCH(2)
NAME top
inotify_rm_watch - remove an existing watch from an inotify instance
SYNOPSIS top
#include <sys/inotify.h> int inotify_rm_watch(int fd, int wd);
DESCRIPTION top
inotify_rm_watch() removes the watch associated with the watch descriptor wd from the inotify instance associated with the file descriptor fd. Removing a watch causes an IN_IGNORED event to be generated for this watch descriptor. (See inotify(7).)
RETURN VALUE top
On success, inotify_rm_watch() returns zero. On error, -1 is returned and errno is set to indicate the cause of the error.
ERRORS top
EBADF fd is not a valid file descriptor. EINVAL The watch descriptor wd is not valid; or fd is not an inotify file descriptor.
VERSIONS top
Inotify was merged into the 2.6.13 Linux kernel.
CONFORMING TO top
This system call is Linux-specific.
SEE ALSO top
inotify_add_watch(2), inotify_init(2), inotify(7)
COLOPHON top
This page is part of release 3.69 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 2010-10-15 INOTIFY_RM_WATCH(2)
英文:http://linux.die.net/man/2/inotify_add_watch
notify是什么?用它能干些什么?
通俗点说它是一个内核用于通知用户空间程序文件系统变化的系统,并且它是powerful yet simple的。
inotify的用户接口原型主要有以下3个:
#include <sys/inotify.h>
初始化:int inotify_init(void);
int fd = inotify_init();
添加监视对象:int inotify_add_watch(int fd, const char *path, uint32_t mask);
int wd = inotify_add_watch(fd,path,mask);
fd是inotify_init()的返回值。
const char *path是要监控的文件(目录)的路径。
uint32_t mask是:
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