β

如何列出所有的 Bash Shell 内置命令

Linux.中国 - 开源中文社区 18 阅读

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

  1. Bourne Shell 内置命令:内置命令继承自 Bourne Shell。
  2. Bash 内置命令:特定于 Bash 的内置命令表。
  3. 修改 Shell 行为:修改 shell 属性和可选行为的内置命令。
  4. 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。可以在 Twitter Facebook Google+ 上关注他。


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

作者: Vivek Gite 译者: KarenMrzhang 校对: wxy

本文由 LCTT 原创编译, Linux中国 荣誉推出

作者:Linux.中国 - 开源中文社区
Linux.中国 - 开源中文社区
原文地址:如何列出所有的 Bash Shell 内置命令, 感谢原作者分享。

发表评论