shell 內建命令就是乙個命令或乙個函式，從 shell 中呼叫，它直接在 shell 中執行。 bash shell 直接執行該命令而無需呼叫其他程式。你可以使用 help 命令檢視 bash 內建命令的資訊。以下是幾種不同型別的內建命令。
內建命令的型別
型別如下：
bourne shell 內建命令：內建命令繼承自 bourne shell。
bash 內建命令：特定於 bash 的內建命令表。
修改 shell 行為：修改 shell 屬性和可選行為的內建命令。
特別的內建命令：由 posix 特別分類的內建命令。
如何檢視所有 bash 內建命令
有以下的命令：
$ help樣例輸出：$ help | less
$ help | grep read
gnu bash, version 4.1.5(1)-release (x86_64-pc-linux-gnu)另外一種選擇是使用下列命令：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 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 ...]
compgen -b檢視 bash 的內建命令資訊compgen -b | more
執行以下得到詳細資訊：
help command要僅得到所有帶簡短描述的內建命令的列表，執行如下:help read
$ help -d查詢內建命令的語法和其他選項
help name樣例輸出：help cd
help fg
help for
help read
help :
:: :找出乙個命令是內部的（內建）還是外部的null command.
no effect; the command does nothing.
exit status:
always succeeds
使用 type 命令或 command 命令：
type -a command-name-here或者：type -a cd
type -a uname
type -a :
type -a ls
type -a cd uname : ls uname樣例輸出：
cd is a shell builtin或者：uname is /bin/uname
: is a shell builtin
ls is aliased to `ls --color=auto'
ls is /bin/ls
l is a function
l ()
command -v ls本文由 lctt 原創翻譯，linux中國 榮譽推出command -v cd
command -v foo
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