解读Linux命令格式(转)

解读Linux命令格式

 

环境

Linux HA5-139JK 2.6.18-164.el5 #1 SMP Tue Aug 18 15:51:48 EDT 2009 x86_64 x86_64 x86_64 GNU/Linux

 

Linux命令很多，但对格式本身解读的文章几乎是空白，都在凭对格式的猜测来写命令，就此在网上搜集此类资料都很少而且很不全面，想找官方的，也没找到。根据自己的理解写一篇出来，希望对初学者有用。

 

一、命令的一般格式

 

command [options] [arguments]

 

command：命令

options：--单词   或   -单字

arguments：参数，有时候选项也带参数。

 

二、命令格式中的符号含义

 

在查看命令帮助时，会出现[],<>,|等符号，它们的含义如下：

[]       表示是可选的;

<>       表示可变选项，一般是多选一，而且必须是要选其一。

x|y|z    多选一，如果加上[]，可不选。

-abc     多选，如果加上[]，可不选。

 

三、常见命令格式的举例说明

 

对于命令格式中常常可以看到如下的格式：

1、[ --atime-preserve  ]，表示一个可选选项。

2、[ -B, --read-full-records ]，表示一个可选选项，简写为-B，完整写法是--read-full-records，两者在用的时候只能选择其一，它们的功能都是完全一样的。一般带“-”开头的选项都是简写，“--”开头的命令都是完整写法，并且，一般的选择都有一个简写，一个完整写法，简写写在前面，完整写法写在后面，中间用逗号分割。

3、[ -b, --blocking-factor N ]，表示一个可选选项，简写为-b N，完整写法是--blocking-factor N，N代表这个参数需要一个值，在详细描述中可以看到。当然，选项可以带参数，也可以不带参数，大部分选项是没有参数的，相当于控制开关。命令的书写如：tar -b=10000 -cvf com.tar.gz com

4、[ -F, --info-script  F  --new-volume-script  F  ]，表示有两个同时存在的可选命令，-F F --new-volume-script F，两个选项必须同时出现，在此，后面的选项没有简写。

5、[ -z, --gzip, --gunzip, --ungzip ]，表示一个可选选项，它的写法有多种，除了-z之外，其他的都是它的完整写法。

6、[ -[0-7][lmh] ]，表示嵌套的可选选项，0-7表示取值从0到7取一个。

 

四、通过tar命令行来解读Unix命令：

 

[kf139@HA5-139JK bin]$ man tar

TAR(1)                                tar                               TAR(1)

 

NAME（名称）

       tar - The GNU version of the tar archiving utility

 

SYNOPSIS（大纲）

       tar <operation> [options]

 

       Operations:（操作选项）

       [-]A --catenate --concatenate

       [-]c --create

       [-]d --diff --compare

       [-]r --append

       [-]t --list

       [-]u --update

       [-]x --extract --get

       --delete

 

       Common Options:（公共选项）

       -C, --directory DIR

       -f, --file F

       -j, --bzip2

       -p, --preserve-permissions

       -v, --verbose

       -z, --gzip

 

       All Options:（所有选项）

       [  --atime-preserve  ]  [  -b,  --blocking-factor  N ] [ -B, --read-full-records ] [ --backup BACKUP-TYPE ] [ --block-compress ] [ -C,

       --directory DIR ] [ --check-links ] [ --checkpoint ] [ -f, --file [HOSTNAME:]F ] [ -F,  --info-script  F  --new-volume-script  F  ]  [

       --force-local    ]  [ --format FORMAT ] [ -g, --listed-incremental F ] [ -G, --incremental ] [ --group GROUP ] [ -h, --dereference ] [

       --help ] [ -i, --ignore-zeros ] [ --ignore-case ] [ --ignore-failed-read ] [ --index-file FILE ] [ -j, --bzip2  ]  [  -k,  --keep-old-

       files  ] [ -K, --starting-file F ] [ --keep-newer-files ] [ -l, --one-file-system ] [ -L, --tape-length N ] [ -m, --touch, --modifica-

       tion-time ] [ -M, --multi-volume ] [ --mode PERMISSIONS ] [ -N, --after-date DATE, --newer DATE ]  [  --newer-mtime  DATE  ]  [  --no-

       anchored  ]  [  --no-ignore-case  ]  [  --no-recursion ] [ --no-same-permissions ] [ --no-wildcards ] [ --no-wildcards-match-slash ] [

       --null     ] [ --numeric-owner ] [ -o, --old-archive, --portability, --no-same-owner ] [ -O, --to-stdout ]  [  --occurrence  NUM  ]  [

       --overwrite  ]  [  --overwrite-dir  ]  [  --owner USER ] [ -p, --same-permissions, --preserve-permissions ] [ -P, --absolute-names ] [

       --pax-option KEYWORD-LIST ] [ --posix ] [ --preserve ] [ --acls ] [ --selinux ] [ --xattrs ] [ --no-acls ] [ --no-selinux  ]  [  --no-

       xattrs ] [ -R, --block-number ] [ --record-size SIZE ] [ --recursion ] [ --recursive-unlink ] [ --remove-files ] [ --rmt-command CMD ]

       [ --rsh-command CMD ] [ -s, --same-order, --preserve-order ] [ -S, --sparse ] [ --same-owner ] [ --show-defaults ]  [  --show-omitted-

       dirs  ]  [  --strip-components  NUMBER,  --strip-path  NUMBER  (1)  ]  [ --suffix SUFFIX ] [ -T, --files-from F ] [ --totals   ] [ -U,

       --unlink-first ] [ --use-compress-program PROG ] [ --utc ] [ -v, --verbose ] [ -V, --label NAME ] [ --version  ] [ --volno-file F ]  [

       -w,  --interactive,  --confirmation  ]  [  -W,  --verify  ]  [  --wildcards  ] [ --wildcards-match-slash ] [ --exclude PATTERN ] [ -X,

       --exclude-from FILE ] [ -Z, --compress, --uncompress ] [ -z, --gzip, --gunzip, --ungzip ] [ -[0-7][lmh] ]

 

       (1) tar-1.14 uses --strip-path, tar-1.14.90+ uses --strip-components

 

DESCRIPTION（描述）

       This manual page documents the GNU version of tar, an archiving program designed to store and extract files from an archive file known

       as a tarfile.  A tarfile may be made on a tape drive, however, it is also common to write a tarfile to a normal file.  The first argu-

       ment to tar must be one of the options Acdrtux, followed by any optional functions.  The final arguments to tar are the names  of  the

       files  or  directories  which  should be archived.  The use of a directory name always implies that the subdirectories below should be

       included in the archive.

 

EXAMPLES（例子）

       tar -xvf foo.tar

              verbosely extract foo.tar

 

       tar -xzf foo.tar.gz

              extract gzipped foo.tar.gz

 

       tar -cjf foo.tar.bz2 bar/

              create bzipped tar archive of the directory bar called foo.tar.bz2

 

       tar -xjf foo.tar.bz2 -C bar/

              extract bzipped foo.tar.bz2 after changing directory to bar

 

       tar -xzf foo.tar.gz blah.txt

              extract the file blah.txt from foo.tar.gz

 

FUNCTION LETTERS（功能选项）

       One of the following options must be used:

 

       -A, --catenate, --concatenate

              append tar files to an archive

 

       -c, --create

              create a new archive

 

       -d, --diff, --compare

              find differences between archive and file system

 

       -r, --append

              append files to the end of an archive

 

       -t, --list

              list the contents of an archive

 

       -u, --update

              only append files that are newer than the existing in archive

 

       -x, --extract, --get

              extract files from an archive

 

       --delete

              delete from the archive (not for use on mag tapes!)

 

COMMON OPTIONS（公共选项）

       -C, --directory DIR

              change to directory DIR

 

       -f, --file [HOSTNAME:]F

              use archive file or device F (default "-", meaning stdin/stdout)

 

       -j, --bzip2

              filter archive through bzip2, use to decompress .bz2 files

 

       -p, --preserve-permissions

              extract all protection information

 

       -v, --verbose

              verbosely list files processed

 

       -z, --gzip, --ungzip

              filter the archive through gzip

 

ALL OPTIONS（所有选项）

       --atime-preserve

              don’t change access times on dumped files

 

       -b, --blocking-factor N

              block size of Nx512 bytes (default N=20)

 

       -B, --read-full-blocks

              reblock as we read (for reading 4.2BSD pipes)

 

       --backup BACKUP-TYPE

              backup files instead of deleting them using BACKUP-TYPE simple or numbered

 

       --block-compress

              block the output of compression program for tapes

 

       -C, --directory DIR

              change to directory DIR

 

       --check-links

              warn if number of hard links to the file on the filesystem mismatch the number of links recorded in the archive

 

       --checkpoint

              print directory names while reading the archive

 

       -f, --file [HOSTNAME:]F

              use archive file or device F (default "-", meaning stdin/stdout)

 

       -F, --info-script F --new-volume-script F

              run script at end of each tape (implies --multi-volume)

 

       --force-local

              archive file is local even if has a colon

 

       --format FORMAT

              selects output archive format

              v7 - Unix V7

              oldgnu - GNU tar <=1.12

              gnu - GNU tar 1.13

              ustar - POSIX.1-1988

              posix - POSIX.1-2001

 

       -g, --listed-incremental F

              create/list/extract new GNU-format incremental backup

 

       -G, --incremental

              create/list/extract old GNU-format incremental backup

 

       -h, --dereference

              don’t dump symlinks; dump the files they point to

 

       --help like this manpage, but not as cool

 

       -i, --ignore-zeros

              ignore blocks of zeros in archive (normally mean EOF)

 

       --ignore-case

              ignore case when excluding files

 

       --ignore-failed-read

              don’t exit with non-zero status on unreadable files

 

       --index-file FILE

              send verbose output to FILE instead of stdout

 

       -j, --bzip2

              filter archive through bzip2, use to decompress .bz2 files

 

       -k, --keep-old-files

              keep existing files; don’t overwrite them from archive

 

       -K, --starting-file F

              begin at file F in the archive

 

       --keep-newer-files

              do not overwrite files which are newer than the archive

 

       -l, --one-file-system

              stay in local file system when creating an archive

 

       -L, --tape-length N

              change tapes after writing N*1024 bytes

 

       -m, --touch, --modification-time

              don’t extract file modified time

 

       -M, --multi-volume

              create/list/extract multi-volume archive

 

       --mode PERMISSIONS

              apply PERMISSIONS while adding files (see chmod(1))

 

       -N, --after-date DATE, --newer DATE

              only store files newer than DATE

 

       --newer-mtime DATE

              like --newer, but with a DATE

 

       --no-anchored

              match any subsequenceof the name’s components with --exclude

 

       --no-ignore-case

              use case-sensitive matching with --exclude

 

       --no-recursion

              don’t recurse into directories

 

       --no-same-permissions

              apply user’s umask when extracting files instead of recorded permissions

 

       --no-wildcards

              don’t use wildcards with --exclude

 

       --no-wildcards-match-slash

              wildcards do not match slashes (/) with --exclude

 

       --null --files-from reads null-terminated names, disable --directory

 

       --numeric-owner

              always use numbers for user/group names

 

       -o, --old-archive, --portability

              like --format=v7; -o exhibits this behavior when creating an archive (deprecated behavior)

 

       -o, --no-same-owner

              do not attempt to restore ownership when extracting; -o exhibits this behavior when extracting an archive

 

       -O, --to-stdout

              extract files to standard output

 

       --occurrence NUM

              process only NUM occurrences of each named file; used with --delete, --diff, --extract, or --list

 

       --overwrite

              overwrite existing files and directory metadata when extracting

 

       --overwrite-dir

              overwrite directory metadata when extracting

 

       --owner USER

              change owner of extraced files to USER

 

       -p, --same-permissions, --preserve-permissions

              extract all protection information

 

       -P, --absolute-names

              don’t strip leading ‘/’s from file names

 

       --pax-option KEYWORD-LIST

              used only with POSIX.1-2001 archives to modify the way tar handles extended header keywords

 

       --posix

              like --format=posix

 

       --preserve

              like --preserve-permissions --same-order

 

       --acls this option causes tar to store each file’s ACLs in the archive.

 

       --selinux

              this option causes tar to store each file’s SELinux security context information in the archive.

 

       --xattrs

              this option causes tar to store each file’s extended attributes in the archive. This option also enables --acls and--selinux if

              they haven’t been set already, due to the fact that the data for those are stored in special xattrs.

 

       --no-acls

              This option causes tar not to store each file’s ACLs in the archive and not to extract any ACL information in an archive.

 

       --no-selinux

              this  option  causes  tar  not  to store each file’s SELinux security context information in the archive and not to extract any

              SELinux information in an archive.

 

       --no-xattrs

              this option causes tar not to store each file’s extended attributes in the archive and not to extract any  extended  attributes

              in an archive. This option also enables --no-acls and --no-selinux if they haven’t been set already.

 

       -R, --record-number

              show record number within archive with each message

 

       --record-size SIZE

              use SIZE bytes per record when accessing archives

 

       --recursion

              recurse into directories

 

       --recursive-unlink

              remove existing directories before extracting directories of the same name

 

       --remove-files

              remove files after adding them to the archive

 

       --rmt-command CMD

              use CMD instead of the default /usr/sbin/rmt

 

       --rsh-command CMD

              use remote CMD instead of rsh(1)

 

       -s, --same-order, --preserve-order

              list of names to extract is sorted to match archive

 

       -S, --sparse

              handle sparse files efficiently

 

       --same-owner

              create extracted files with the same ownership

 

       --show-defaults

              display the default options used by tar

 

       --show-omitted-dirs

              print directories tar skips while operating on an archive

 

       --strip-components NUMBER, --strip-path NUMBER

              strip NUMBER of leading components from file names before extraction

 

              (1) tar-1.14 uses --strip-path, tar-1.14.90+ uses --strip-components

 

       --suffix SUFFIX

              use SUFFIX instead of default ’~’ when backing up files

 

       -T, --files-from F

              get names to extract or create from file F

 

       --totals

              print total bytes written with --create

 

       -U, --unlink-first

              remove existing files before extracting files of the same name

 

       --use-compress-program PROG

              access the archive through PROG which is generally a compression program

 

       --utc  display file modification dates in UTC

 

       -v, --verbose

              verbosely list files processed

 

       -V, --label NAME

              create archive with volume name NAME

 

       --version

              print tar program version number

 

       --volno-file F

              keep track of which volume of a multi-volume archive its working in FILE; used with --multi-volume

 

       -w, --interactive, --confirmation

              ask for confirmation for every action

 

       -W, --verify

              attempt to verify the archive after writing it

 

       --wildcards

              use wildcards with --exclude

 

       --wildcards-match-slash

              wildcards match slashes (/) with --exclude

 

       --exclude PATTERN

              exclude files based upon PATTERN

 

       -X, --exclude-from FILE

              exclude files listed in FILE

 

       -Z, --compress, --uncompress

              filter the archive through compress

 

       -z, --gzip, --gunzip, --ungzip

              filter the archive through gzip

 

       --use-compress-program PROG

              filter the archive through PROG (which must accept -d)

 

       -[0-7][lmh]

              specify drive and density

 

BUGS（缺陷）

       The  GNU folks, in general, abhor man pages, and create info documents instead.  The maintainer of tar falls into this category.  Thus

       this man page may not be complete, nor current, and was included in the Red Hat CVS tree because man is a great  tool  :).   This  man

       page was first taken from Debian Linux and has since been loving updated here.

 

REPORTING BUGS（报道中的缺陷）

       Please report bugs via https://bugzilla.redhat.com

 

SEE ALSO（参考）

       The  full  documentation for tar is maintained as a Texinfo manual.  If the info and tar programs are properly installed at your site,

       the command

 

              info tar

 

       should give you access to the complete manual.

 

AUTHORS（作者）

       Debian Linux http://www.debian.org/

       Mike Frysinger <vapier@gentoo.org>

 

GNU                                Oct 2004                             TAR(1)

 

上面的tar命令用法很复杂，可以看个简单的rm删除命令：

 

[kf139@HA5-139JK bin]$ man rm

RM(1)                            User Commands                           RM(1)

 

NAME

       rm - remove files or directories

 

SYNOPSIS

       rm [OPTION]... FILE...

 

DESCRIPTION

       This manual page documents the GNU version of rm.  rm removes each specified file.  By default, it does not remove directories.

 

       If  a  file  is unwritable, the standard input is a tty, and the -f or --force option is not given, rm prompts the user for whether to

       remove the file.  If the response is not affirmative, the file is skipped.

 

OPTIONS

       Remove (unlink) the FILE(s).

 

       -f, --force

              ignore nonexistent files, never prompt

 

       -i, --interactive

              prompt before any removal

 

       --no-preserve-root do not treat ‘/’ specially (the default)

 

       --preserve-root

              fail to operate recursively on ‘/’

 

       -r, -R, --recursive

              remove directories and their contents recursively

 

       -v, --verbose

              explain what is being done

 

       --help display this help and exit

 

       --version

              output version information and exit

 

       By default, rm does not remove directories.  Use the --recursive (-r or -R) option to remove each listed directory,  too,  along  with

       all of its contents.

 

       To remove a file whose name starts with a ‘-’, for example ‘-foo’, use one of these commands:

 

              rm -- -foo

 

              rm ./-foo

 

       Note  that  if  you  use rm to remove a file, it is usually possible to recover the contents of that file.  If you want more assurance

       that the contents are truly unrecoverable, consider using shred.

 

AUTHOR

       Written by Paul Rubin, David MacKenzie, Richard Stallman, and Jim Meyering.

 

REPORTING BUGS

       Report bugs to <bug-coreutils@gnu.org>.

 

COPYRIGHT

       Copyright (C) 2006 Free Software Foundation, Inc.

       This  is  free  software.   You  may  redistribute  copies  of  it   under   the   terms   of   the   GNU   General   Public   License

       <http://www.gnu.org/licenses/gpl.html>.  There is NO WARRANTY, to the extent permitted by law.

 

SEE ALSO

       chattr(1), shred(1)

 

       The full documentation for rm is maintained as a Texinfo manual.  If the info and rm programs are properly installed at your site, the

       command

 

              info rm

 

       should give you access to the complete manual.

 

rm 5.97                            July 2009                             RM(1)

 

五、Linux命令和Unix命令格式大致都一样，不同的系统，命令也可能不同。有些命令虽然选项很多，但不一定全支持。用的时候还是多试试为好，实践才是最可靠的检验标准，本文旨在让初学者能快速看懂man打印出命令帮助。欢迎拍砖！

 

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