shell 內建指令就是一個指令或一個函數，從 shell 中調用，它直接在 shell 中執行。 bash shell 直接執行該指令而無需呼叫其他程式。你可以使用 help 指令來查看 Bash 內建指令的資訊。以下是幾種不同類型的內建指令。
#類型如下：
Bourne Shell 內建指令：內建指令繼承自 Bourne Shell。
Bash 內建指令：特定於 Bash 的內建指令表。
修改 Shell 行為：修改 shell 屬性和可選行為的內建指令。
特別的內建指令：由 POSIX 特別分類的內建指令。
有以下的指令：
$ help $ help | less $ help | grep read
範例輸出：
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指令：
compgen -b compgen -b | more
運行以下得到詳細資訊：
help command help read
要僅得到所有帶有簡短描述的內建指令的列表，執行如下:
$ help -d
使用下列語法去找出更多相關的內建指令：
help name help cd help fg help for help read help :
範例輸出：
:: : Null command. No effect; the command does nothing. Exit Status: Always succeeds
#使用 type 指令或 command 指令：
type -a command-name-here type -a cd type -a uname type -a : type -a ls
或：
type -a cd uname : ls uname
範例輸出：
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：
command -V ls command -V cd command -V foo
#
作者：Vivek Gite
以上是列出所有的 Bash Shell 內建指令的詳細內容。更多資訊請關注PHP中文網其他相關文章！
