列出所有的 Bash Shell 内置命令

导读 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

类型如下:
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


作者:Vivek Gite 译者:KarenMrzhang 校对:wxy

本文由 LCTT 原创翻译,Linux中国 荣誉推出

本文原创地址:https://www.linuxprobe.com/bash-shell-command.html编辑:张@宇,审核员:暂无

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