【手册】Linux User's Manual

原文章地址：The Linux man-pages project

Linux User’s Manual(1) - user commands

NAME

       intro - introduction to user commands

DESCRIPTION

       Section 1 of the manual describes user commands and tools, for       example, file manipulation tools, shells, compilers, web browsers,       file and image viewers and editors, and so on.

NOTES

       Linux is a flavor of UNIX, and as a first approximation all user       commands under UNIX work precisely the same under Linux (and FreeBSD       and lots of other UNIX-like systems).       Under Linux, there are GUIs (graphical user interfaces), where you       can point and click and drag, and hopefully get work done without       first reading lots of documentation.  The traditional UNIX       environment is a CLI (command line interface), where you type       commands to tell the computer what to do.  That is faster and more       powerful, but requires finding out what the commands are.  Below a       bare minimum, to get started.   Login       In order to start working, you probably first have to open a session       by giving your username and password.  The program login(1) now       starts a shell (command interpreter) for you.  In case of a graphical       login, you get a screen with menus or icons and a mouse click will       start a shell in a window.  See also xterm(1).   The shell       One types commands to the shell, the command interpreter.  It is not       built-in, but is just a program and you can change your shell.       Everybody has her own favorite one.  The standard one is called sh.       See also ash(1), bash(1), chsh(1), csh(1), dash(1), ksh(1), zsh(1).       A session might go like:              knuth login: aeb              Password: ********              $ date              Tue Aug  6 23:50:44 CEST 2002              $ cal                   August 2002              Su Mo Tu We Th Fr Sa                           1  2  3               4  5  6  7  8  9 10              11 12 13 14 15 16 17              18 19 20 21 22 23 24              25 26 27 28 29 30 31              $ ls              bin  tel              $ ls -l              total 2              drwxrwxr-x   2 aeb       1024 Aug  6 23:51 bin              -rw-rw-r--   1 aeb         37 Aug  6 23:52 tel              $ cat tel              maja    0501-1136285              peter   0136-7399214              $ cp tel tel2              $ ls -l              total 3              drwxr-xr-x   2 aeb       1024 Aug  6 23:51 bin              -rw-r--r--   1 aeb         37 Aug  6 23:52 tel              -rw-r--r--   1 aeb         37 Aug  6 23:53 tel2              $ mv tel tel1              $ ls -l              total 3              drwxr-xr-x   2 aeb       1024 Aug  6 23:51 bin              -rw-r--r--   1 aeb         37 Aug  6 23:52 tel1              -rw-r--r--   1 aeb         37 Aug  6 23:53 tel2              $ diff tel1 tel2              $ rm tel1              $ grep maja tel2              maja    0501-1136285              $       Here typing Control-D ended the session.       The $ here was the command prompt—it is the shell's way of indicating       that it is ready for the next command.  The prompt can be customized       in lots of ways, and one might include stuff like username, machine       name, current directory, time, and so on.  An assignment PS1="What       next, master? " would change the prompt as indicated.       We see that there are commands date (that gives date and time), and       cal (that gives a calendar).       The command ls lists the contents of the current directory—it tells       you what files you have.  With a -l option it gives a long listing,       that includes the owner and size and date of the file, and the       permissions people have for reading and/or changing the file.  For       example, the file "tel" here is 37 bytes long, owned by aeb and the       owner can read and write it, others can only read it.  Owner and       permissions can be changed by the commands chown and chmod.       The command cat will show the contents of a file.  (The name is from       "concatenate and print": all files given as parameters are       concatenated and sent to "standard output" (see stdout(3)), here the       terminal screen.)       The command cp (from "copy") will copy a file.       The command mv (from "move"), on the other hand, only renames it.       The command diff lists the differences between two files.  Here there       was no output because there were no differences.       The command rm (from "remove") deletes the file, and be careful! it       is gone.  No wastepaper basket or anything.  Deleted means lost.       The command grep (from "g/re/p") finds occurrences of a string in one       or more files.  Here it finds Maja's telephone number.   Pathnames and the current directory       Files live in a large tree, the file hierarchy.  Each has a pathname       describing the path from the root of the tree (which is called /) to       the file.  For example, such a full pathname might be /home/aeb/tel.       Always using full pathnames would be inconvenient, and the name of a       file in the current directory may be abbreviated by giving only the       last component.  That is why /home/aeb/tel can be abbreviated to tel       when the current directory is /home/aeb.       The command pwd prints the current directory.       The command cd changes the current directory.       Try alternatively cd and pwd commands and explore cd usage: "cd", "cd       .", "cd ..", "cd /" and "cd ~".   Directories       The command mkdir makes a new directory.       The command rmdir removes a directory if it is empty, and complains       otherwise.       The command find (with a rather baroque syntax) will find files with       given name or other properties.  For example, "find . -name tel"       would find the file tel starting in the present directory (which is       called .).  And "find / -name tel" would do the same, but starting at       the root of the tree.  Large searches on a multi-GB disk will be       time-consuming, and it may be better to use locate(1).   Disks and filesystems       The command mount will attach the filesystem found on some disk (or       floppy, or CDROM or so) to the big filesystem hierarchy.  And umount       detaches it again.  The command df will tell you how much of your       disk is still free.   Processes       On a UNIX system many user and system processes run simultaneously.       The one you are talking to runs in the foreground, the others in the       background.  The command ps will show you which processes are active       and what numbers these processes have.  The command kill allows you       to get rid of them.  Without option this is a friendly request:       please go away.  And "kill -9" followed by the number of the process       is an immediate kill.  Foreground processes can often be killed by       typing Control-C.   Getting information       There are thousands of commands, each with many options.       Traditionally commands are documented on man pages, (like this one),       so that the command "man kill" will document the use of the command       "kill" (and "man man" document the command "man").  The program man       sends the text through some pager, usually less.  Hit the space bar       to get the next page, hit q to quit.       In documentation it is customary to refer to man pages by giving the       name and section number, as in man(1).  Man pages are terse, and       allow you to find quickly some forgotten detail.  For newcomers an       introductory text with more examples and explanations is useful.       A lot of GNU/FSF software is provided with info files.  Type "info       info" for an introduction on the use of the program info.       Special topics are often treated in HOWTOs.  Look in       /usr/share/doc/howto/en and use a browser if you find HTML files       there.

SEE ALSO

       ash(1), bash(1), chsh(1), csh(1), dash(1), ksh(1), locate(1),       login(1), man(1), xterm(1), zsh(1), wait(2), stdout(3), man-pages(7),       standards(7)

COLOPHON

       This page is part of release 4.11 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       https://www.kernel.org/doc/man-pages/.Linux                            2015-07-23                         INTRO(1)

Linux User’s Manual(2) - system calls

NAME

       intro - introduction to system calls

DESCRIPTION

       Section 2 of the manual describes the Linux system calls.  A system       call is an entry point into the Linux kernel.  Usually, system calls       are not invoked directly: instead, most system calls have       corresponding C library wrapper functions which perform the steps       required (e.g., trapping to kernel mode) in order to invoke the       system call.  Thus, making a system call looks the same as invoking a       normal library function.       In many cases, the C library wrapper function does nothing more than:       *  copying arguments and the unique system call number to the          registers where the kernel expects them;       *  trapping to kernel mode, at which point the kernel does the real          work of the system call;       *  setting errno if the system call returns an error number when the          kernel returns the CPU to user mode.       However, in a few cases, a wrapper function may do rather more than       this, for example, performing some preprocessing of the arguments       before trapping to kernel mode, or postprocessing of values returned       by the system call.  Where this is the case, the manual pages in       Section 2 generally try to note the details of both the (usually GNU)       C library API interface and the raw system call.  Most commonly, the       main DESCRIPTION will focus on the C library interface, and       differences for the system call are covered in the NOTES section.       For a list of the Linux system calls, see syscalls(2).

RETURN VALUE

       On error, most system calls return a negative error number (i.e., the       negated value of one of the constants described in errno(3)).  The C       library wrapper hides this detail from the caller: when a system call       returns a negative value, the wrapper copies the absolute value into       the errno variable, and returns -1 as the return value of the       wrapper.       The value returned by a successful system call depends on the call.       Many system calls return 0 on success, but some can return nonzero       values from a successful call.  The details are described in the       individual manual pages.       In some cases, the programmer must define a feature test macro in       order to obtain the declaration of a system call from the header file       specified in the man page SYNOPSIS section.  (Where required, these       feature test macros must be defined before including any header       files.)  In such cases, the required macro is described in the man       page.  For further information on feature test macros, see       feature_test_macros(7).

CONFORMING TO

       Certain terms and abbreviations are used to indicate UNIX variants       and standards to which calls in this section conform.  See       standards(7).

NOTES

   Calling directly       In most cases, it is unnecessary to invoke a system call directly,       but there are times when the Standard C library does not implement a       nice wrapper function for you.  In this case, the programmer must       manually invoke the system call using syscall(2).  Historically, this       was also possible using one of the _syscall macros described in       _syscall(2).   Authors and copyright conditions       Look at the header of the manual page source for the author(s) and       copyright conditions.  Note that these can be different from page to       page!

SEE ALSO

       _syscall(2), syscall(2), syscalls(2), errno(3), intro(3),       capabilities(7), credentials(7), feature_test_macros(7),       mq_overview(7), path_resolution(7), pipe(7), pty(7), sem_overview(7),       shm_overview(7), signal(7), socket(7), standards(7), svipc(7),       symlink(7), time(7)

COLOPHON

       This page is part of release 4.11 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       https://www.kernel.org/doc/man-pages/.Linux                            2014-02-20                         INTRO(2)

Linux User’s Manual(3) - library functions

NAME

       intro - introduction to library functions

DESCRIPTION

       Section 3 of the manual describes all library functions excluding the       library functions (system call wrappers) described in Section 2,       which implement system calls.       Many of the functions described in the section are part of the       Standard C Library (libc).  Some functions are part of other       libraries (e.g., the math library, libm, or the real-time library,       librt) in which case the manual page will indicate the linker option       needed to link against the required library (e.g., -lm and -lrt,       respectively, for the aforementioned libraries).       In some cases, the programmer must define a feature test macro in       order to obtain the declaration of a function from the header file       specified in the man page SYNOPSIS section.  (Where required, these       feature test macros must be defined before including any header       files.)  In such cases, the required macro is described in the man       page.  For further information on feature test macros, see       feature_test_macros(7).

CONFORMING TO

       Certain terms and abbreviations are used to indicate UNIX variants       and standards to which calls in this section conform.  See       standards(7).

NOTES

   Authors and copyright conditions       Look at the header of the manual page source for the author(s) and       copyright conditions.  Note that these can be different from page to       page!

SEE ALSO

       intro(2), errno(3), capabilities(7), credentials(7), environ(7),       feature_test_macros(7), libc(7), math_error(7), path_resolution(7),       pthreads(7), signal(7), standards(7)

COLOPHON

       This page is part of release 4.11 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       https://www.kernel.org/doc/man-pages/.Linux                            2010-11-11                         INTRO(3)

Linux User’s Manual(4) - special files

NAME

       intro - introduction to special files

DESCRIPTION

       Section 4 of the manual describes special files (devices).

FILES

       /dev/* — device files

NOTES

   Authors and copyright conditions       Look at the header of the manual page source for the author(s) and       copyright conditions.  Note that these can be different from page to       page!

SEE ALSO

       standards(7)

COLOPHON

       This page is part of release 4.11 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       https://www.kernel.org/doc/man-pages/.Linux                            2007-10-23                         INTRO(4)

Linux User’s Manual(5) - file formats and filesystems

NAME

       intro - introduction to file formats and filesystems

DESCRIPTION

       Section 5 of the manual describes various file formats, as well as       the corresponding C structures, if any.  In addition, there are a       number of pages that document various filesystems.

NOTES

   Authors and copyright conditions       Look at the header of the manual page source for the author(s) and       copyright conditions.  Note that these can be different from page to       page!

SEE ALSO

       standards(7)

COLOPHON

       This page is part of release 4.11 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       https://www.kernel.org/doc/man-pages/.Linux                            2017-03-13                         INTRO(5)

Linux User’s Manual(6) - games

NAME

       intro - introduction to games

DESCRIPTION

       Section 6 of the manual describes all the games and funny little       programs available on the system.

NOTES

   Authors and copyright conditions       Look at the header of the manual page source for the author(s) and       copyright conditions.  Note that these can be different from page to       page!

COLOPHON

       This page is part of release 4.11 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       https://www.kernel.org/doc/man-pages/.Linux                            2007-10-23                         INTRO(6)

Linux User’s Manual(7) - overview, conventions, and miscellany section

NAME

       intro - introduction to overview, conventions, and miscellany section

DESCRIPTION

       Section 7 of the manual provides overviews on various topics, and       describes conventions and protocols, character set standards, the       standard filesystem layout, and miscellaneous other things.

NOTES

   Authors and copyright conditions       Look at the header of the manual page source for the author(s) and       copyright conditions.  Note that these can be different from page to       page!

SEE ALSO

       standards(7)

COLOPHON

       This page is part of release 4.11 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       https://www.kernel.org/doc/man-pages/.Linux                            2007-10-23                         INTRO(7)

Linux User’s Manual(8) - administration and privileged commands

NAME

       intro - introduction to administration and privileged commands

DESCRIPTION

       Section 8 of the manual describes commands which either can be or are       used only by the superuser, like system-administration commands,       daemons, and hardware-related commands.       As with the commands described in Section 1, the commands described       in this section terminate with an exit status that indicates whether       the command succeeded or failed.  See intro(1) for more information.

NOTES

   Authors and copyright conditions       Look at the header of the manual page source for the author(s) and       copyright conditions.  Note that these can be different from page to       page!

COLOPHON

       This page is part of release 4.11 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       https://www.kernel.org/doc/man-pages/.Linux                            2007-10-23                         INTRO(8)