Bash Shell 内置命令简介

2018-04-16 18:06:00
Angela
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shell 内置命令就是一个命令或一个函数,从 shell 中调用,它直接在 shell 中执行。 bash shell 直接执行该命令而无需调用其他程序。

-- Vivek Gite


本文导航

◈ 内置命令的类型                                             08%

◈ 如何查看所有 bash 内置命令                         13%

◈ 查看 Bash 的内置命令信息                            61%

◈ 查找内置命令的语法和其他选项                    65%

◈ 找出一个命令是内部的(内置)还是外部的   71%

◈ 关于作者                                                       86%

编译自 | https://www.cyberciti.biz/faq/linux-unix-bash-shell-list-all-builtin-commands/ 
       作者 | Vivek Gite
       译者 | KarenMrzhang

内置命令包含在 bash shell 本身里面。我该如何在 Linux / Apple OS X / *BSD / Unix 类操作系统列出所有的内置 bash 命令,而不用去读大篇的 bash 操作说明页?

shell 内置命令就是一个命令或一个函数,从 shell 中调用,它直接在 shell 中执行。 bash shell 直接执行该命令而无需调用其他程序。你可以使用 help 命令查看 Bash 内置命令的信息。以下是几种不同类型的内置命令。

内置命令的类型

☉ Bourne Shell 内置命令:内置命令继承自 Bourne Shell。

☉ Bash 内置命令:特定于 Bash 的内置命令表。

☉ 修改 Shell 行为:修改 shell 属性和可选行为的内置命令。

☉ 特别的内置命令:由 POSIX 特别分类的内置命令。

如何查看所有 bash 内置命令

有以下的命令:


    $ help
    $ help | less
    $ help | grep read 
样例输出:


    GNU bash, version 4.1.5(1)-release (x86_64-pc-linux-gnu)
    These shell commands are defined internally.  Type `help' to see this list.
    Type `help name' to find out more about the function `name'.
    Use `info bash' to find out more about the shell in general.
    Use `man -k' or `info' to find out more about commands not in this list.

    A star (*) next to a name means that the command is disabled.

     job_spec [&]                            history [-c] [-d offset] [n] or hist>
     (( expression ))                        if COMMANDS; then COMMANDS; [ elif C>
     . filename [arguments]                  jobs [-lnprs] [jobspec ...] or jobs >
     :                                       kill [-s sigspec | -n signum | -sigs>
     [ arg... ]                              let arg [arg ...]
     [[ expression ]]                        local [option] name[=value] ...
     alias [-p] [name[=value] ... ]          logout [n]
     bg [job_spec ...]                       mapfile [-n count] [-O origin] [-s c>
     bind [-lpvsPVS] [-m keymap] [-f filen>  popd [-n] [+N | -N]
     break [n]                               printf [-v var] format [arguments]
     builtin [shell-builtin [arg ...]]       pushd [-n] [+N | -N | dir]
     caller [expr]                           pwd [-LP]
     case WORD in [PATTERN [| PATTERN]...)>  read [-ers] [-a array] [-d delim] [->
     cd [-L|-P] [dir]                        readarray [-n count] [-O origin] [-s>
     command [-pVv] command [arg ...]        readonly [-af] [name[=value] ...] or>
     compgen [-abcdefgjksuv] [-o option]  >  return [n]
     complete [-abcdefgjksuv] [-pr] [-DE] >  select NAME [in WORDS ... ;] do COMM>
     compopt [-o|+o option] [-DE] [name ..>  set [--abefhkmnptuvxBCHP] [-o option>
     continue [n]                            shift [n]
     coproc [NAME] command [redirections]    shopt [-pqsu] [-o] [optname ...]
     declare [-aAfFilrtux] [-p] [name[=val>  source filename [arguments]
     dirs [-clpv] [+N] [-N]                  suspend [-f]
     disown [-h] [-ar] [jobspec ...]         test [expr]
     echo [-neE] [arg ...]                   time [-p] pipeline
     enable [-a] [-dnps] [-f filename] [na>  times
     eval [arg ...]                          trap [-lp] [[arg] signal_spec ...]
     exec [-cl] [-a name] [command [argume>  true
     exit [n]                                type [-afptP] name [name ...]
     export [-fn] [name[=value] ...] or ex>  typeset [-aAfFilrtux] [-p] name[=val>
     false                                   ulimit [-SHacdefilmnpqrstuvx] [limit>
     fc [-e ename] [-lnr] [first] [last] o>  umask [-p] [-S] [mode]
     fg [job_spec]                           unalias [-a] name [name ...]
     for NAME [in WORDS ... ] ; do COMMAND>  unset [-f] [-v] [name ...]
     for (( exp1; exp2; exp3 )); do COMMAN>  until COMMANDS; do COMMANDS; done
     function name { COMMANDS ; } or name >  variables - Names and meanings of so>
     getopts optstring name [arg]            wait [id]
     hash [-lr] [-p pathname] [-dt] [name >  while COMMANDS; do COMMANDS; done
     help [-dms] [pattern ...]               { COMMANDS ; }
另外一种选择是使用下列命令:


    compgen -b
    compgen -b | more


查看 Bash 的内置命令信息

运行以下得到详细信息:


    help command
    help read
要仅得到所有带简短描述的内置命令的列表,执行如下:


    $ help -d


查找内置命令的语法和其他选项

使用下列语法去找出更多的相关内置命令:


    help name 
    help cd 
    help fg 
    help for 
    help read 
    help :
样例输出:


    :: :
     Null command.

     No effect; the command does nothing.

     Exit Status:
     Always succeeds


找出一个命令是内部的(内置)还是外部的

使用 type 命令或 command 命令:


    type -a command-name-here 
    type -a cd 
    type -a uname 
    type -a : 
    type -a ls
或者:


    type -a cd uname : ls uname
样例输出:


    cd is a shell builtin
    uname is /bin/uname
    : is a shell builtin
    ls is aliased to `ls --color=auto'
    ls is /bin/ls
    l is a function
    l ()
    {
     ls --color=auto
    }
或者:


    command -V ls 
    command -V cd 
    command -V foo


View list bash built-ins command info on Linux or Unix

关于作者

作者是 nixCraft 网站的发起人和经验丰富的系统管理员,以及 Linux 操作系统/Unix shell 脚本编程培训师。他与全球客户以及包括 IT、教育、国防和空间研究以及非营利部门在内的各个行业合作。




via: https://www.cyberciti.biz/faq/linux-unix-bash-shell-list-all-builtin-commands/

作者:Vivek Gite 译者:KarenMrzhang 校对:wxy


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