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如何列出所有的 Bash Shell 內置命令

內置命令包含在 bash shell 本身裡面。我該如何在 Linux / Apple OS X / *BSD / Unix 類操作系統列出所有的內置 bash 命令,而不用去讀大篇的 bash 操作說明頁?

shell 內置命令就是一個命令或一個函數,從 shell 中調用,它直接在 shell 中執行。 bash shell 直接執行該命令而無需調用其他程序。你可以使用 help 命令查看 Bash 內置命令的信息。以下是幾種不同類型的內置命令。

內置命令的類型

  1. Bourne Shell 內置命令:內置命令繼承自 Bourne Shell。
  2. Bash 內置命令:特定於 Bash 的內置命令表。
  3. 修改 Shell 行為:修改 shell 屬性和可選行為的內置命令。
  4. 特別的內置命令:由 POSIX 特別分類的內置命令。

如何查看所有 bash 內置命令

有以下的命令:

$ help$ help | less$ help | grep read

樣例輸出:

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 ; }

另外一種選擇是使用下列命令:

compgen -bcompgen -b | more

查看 Bash 的內置命令信息

運行以下得到詳細信息:

help commandhelp read

要僅得到所有帶簡短描述的內置命令的列表,執行如下:

$ help -d

查找內置命令的語法和其他選項

使用下列語法去找出更多的相關內置命令:

help name help cd help fg help for help read help :

樣例輸出:

:: : Null command. No effect; the command does nothing. Exit Status: Always succeeds

找出一個命令是內部的(內置)還是外部的

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

樣例輸出:

cd is a shell builtinuname is /bin/uname: is a shell builtinls is aliased to `ls --color=autols is /bin/lsl is a functionl (){ 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

關於作者

作者是 nixCraft 網站的發起人和經驗豐富的系統管理員,以及 Linux 操作系統/Unix shell 腳本編程培訓師。他與全球客戶以及包括 IT、教育、國防和空間研究以及非營利部門在內的各個行業合作。可以在 Twitter、Facebook、 Google+ 上關注他。


via: cyberciti.biz/faq/linux

作者:Vivek Gite 譯者:KarenMrzhang 校對:wxy

本文由 LCTT 原創編譯,Linux中國 榮譽推出


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