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解读Linux命令格式

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 [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

解读Linux命令格式

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