Linux 终端操作命令（2）内部命令

骑猪看日落 2023-10-14 17:02 10阅读 0赞

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## Linux 终端操作命令 ##

也称Shell命令，是用户与操作系统内核进行交互的命令解释器，它接收用户输入的命令并将其传递给操作系统进行执行，可分为内部命令和外部命令。内部命令是Shell程序的一部分，而外部命令是独立于Shell的可执行程序。

### 内部命令 ###

内部命令，实际上是shell程序的一部分，由shell程序识别并在shell程序内部完成运行，通常在Linux系统加载运行时shell就被加载并驻留在系统内存中。内部命令是写在bash源码里面的，因为解析内部命令shell不需要创建子进程，其执行速度比外部命令快。比如：alias， break， cd， echo， exit， pwd 等。

### 外部命令 ###

外部命令是bash shell之外的程序，也并不是shell的一部分。外部命令位于/bin，/sbin， /usr/bin 或 /usr/sbin 等系统目录中。外部命令是Linux系统中的实用程序部分，因为实用程序的功能通常都比较强大，所以其包含的程序量也会很大，在系统加载时并不随系统一起被加载到内存中，而是在需要时才将其调用内存。通常外部命令的实体并不包含在shell中，但是其命令执行过程是由shell程序控制的。比如： awk， grep， ping，tar， vi 等。 除Linux系统自带的外部命令，通常需要安装对应的程序包才能使用，内部命令之外的所有可执行程序都可以被认作为外部命令。

#### 内外部命令区别 ####

内部命令在系统启动时就调入内存，是常驻内存的，所以执行效率高。

外部命令是系统的软件功能，用户需要时才从硬盘中读入内存，执行速度比内部命令慢。

#### 内部命令列表 ####

help命令可以列出所有内部命令：

hann@HannYang:~$ help  
GNU bash, version 5.0.17(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 history -anrw \[filename\]>  
(( expression )) if COMMANDS; then COMMANDS; \[ elif COMMANDS; then COMMAN>  
. filename \[arguments\] jobs \[-lnprs\] \[jobspec ...\] or jobs -x command \[args\]  
: kill \[-s sigspec | -n signum | -sigspec\] pid | jobspec .>  
\[ arg... \] let arg \[arg ...\]  
\[\[ expression \]\] local \[option\] name\[=value\] ...  
alias \[-p\] \[name\[=value\] ... \] logout \[n\]  
bg \[job\_spec ...\] mapfile \[-d delim\] \[-n count\] \[-O origin\] \[-s count\] \[-t>  
bind \[-lpsvPSVX\] \[-m keymap\] \[-f filename\] \[-q name\] \[-u > 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 \[| PATTERN\]...) COMMANDS ;;\]... esa> read \[-ers\] \[-a array\] \[-d delim\] \[-i text\] \[-n nchars\] >  
cd \[-L|\[-P \[-e\]\] \[-@\]\] \[dir\] readarray \[-d delim\] \[-n count\] \[-O origin\] \[-s count\] \[>  
command \[-pVv\] command \[arg ...\] readonly \[-aAf\] \[name\[=value\] ...\] or readonly -p  
compgen \[-abcdefgjksuv\] \[-o option\] \[-A action\] \[-G globp> return \[n\]  
complete \[-abcdefgjksuv\] \[-pr\] \[-DEI\] \[-o option\] \[-A act> select NAME \[in WORDS ... ;\] do COMMANDS; done  
compopt \[-o|+o option\] \[-DEI\] \[name ...\] set \[-abefhkmnptuvxBCHP\] \[-o option-name\] \[--\] \[arg ...\]  
continue \[n\] shift \[n\]  
coproc \[NAME\] command \[redirections\] shopt \[-pqsu\] \[-o\] \[optname ...\]  
declare \[-aAfFgilnrtux\] \[-p\] \[name\[=value\] ...\] source filename \[arguments\]  
dirs \[-clpv\] \[+N\] \[-N\] suspend \[-f\]  
disown \[-h\] \[-ar\] \[jobspec ... | pid ...\] test \[expr\]  
echo \[-neE\] \[arg ...\] time \[-p\] pipeline  
enable \[-a\] \[-dnps\] \[-f filename\] \[name ...\] times  
eval \[arg ...\] trap \[-lp\] \[\[arg\] signal\_spec ...\]  
exec \[-cl\] \[-a name\] \[command \[arguments ...\]\] \[redirecti> true  
exit \[n\] type \[-afptP\] name \[name ...\]  
export \[-fn\] \[name\[=value\] ...\] or export -p typeset \[-aAfFgilnrtux\] \[-p\] name\[=value\] ...  
false ulimit \[-SHabcdefiklmnpqrstuvxPT\] \[limit\]  
fc \[-e ename\] \[-lnr\] \[first\] \[last\] or fc -s \[pat=rep\] \[c> umask \[-p\] \[-S\] \[mode\]  
fg \[job\_spec\] unalias \[-a\] name \[name ...\]  
for NAME \[in WORDS ... \] ; do COMMANDS; done unset \[-f\] \[-v\] \[-n\] \[name ...\]  
for (( exp1; exp2; exp3 )); do COMMANDS; done until COMMANDS; do COMMANDS; done  
function name \{ COMMANDS ; \} or name () \{ COMMANDS ; \} variables - Names and meanings of some shell variables  
getopts optstring name \[arg\] wait \[-fn\] \[id ...\]  
hash \[-lr\] \[-p pathname\] \[-dt\] \[name ...\] while COMMANDS; do COMMANDS; done  
help \[-dms\] \[pattern ...\] \{ COMMANDS ; \}

通过整理以上内容，得到 68 个命令、函数、变量以及控制指令：

<table style="width:500pt;"> 
 <tbody> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">1</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">alias</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">alias [-p] [name[=value] ... ]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">2</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">bg</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">bg [job_spec ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">3</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">bind</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">bind [-lpsvPSVX] [-m keymap] [-f filename] [-q name] [-u &gt;</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">4</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">break</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">break [n]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">5</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">builtin</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">builtin [shell-builtin [arg ...]]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">6</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">caller</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">caller [expr]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">7</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">case</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">case WORD in [PATTERN [| PATTERN]...) COMMANDS ;;]... esa&gt;</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">8</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">cd</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">cd [-L|[-P [-e]] [-@]] [dir]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">9</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">command</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">command [-pVv] command [arg ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">10</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">compgen</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">compgen [-abcdefgjksuv] [-o option] [-A action] [-G globp&gt;</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">11</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">complete</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">complete [-abcdefgjksuv] [-pr] [-DEI] [-o option] [-A act&gt;</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">12</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">compopt</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">compopt [-o|+o option] [-DEI] [name ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">13</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">continue</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">continue [n]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">14</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">coproc</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">coproc [NAME] command [redirections]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">15</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">declare</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">declare [-aAfFgilnrtux] [-p] [name[=value] ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">16</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">dirs</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">dirs [-clpv] [+N] [-N]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">17</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">disown</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">disown [-h] [-ar] [jobspec ... | pid ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">18</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">echo</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">echo [-neE] [arg ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">19</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">enable</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">enable [-a] [-dnps] [-f filename] [name ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">20</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">eval</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">eval [arg ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">21</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">exec</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">exec [-cl] [-a name] [command [arguments ...]] [redirecti&gt;</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">22</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">exit</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">exit [n]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">23</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">export</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">export [-fn] [name[=value] ...] or export -p</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">24</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">false</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">false</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">25</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">fc</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">fc [-e ename] [-lnr] [first] [last] or fc -s [pat=rep] [c&gt;</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">26</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">fg</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">fg [job_spec]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">27</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">for</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;"> for NAME [in WORDS ... ] ; do COMMANDS; done&nbsp; for (( exp1; exp2; exp3 )); do COMMANDS; done </td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">28</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">function</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">function name { COMMANDS ; } or name () { COMMANDS ; }</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">29</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">getopts</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">getopts optstring name [arg]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">30</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">hash</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">hash [-lr] [-p pathname] [-dt] [name ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">31</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">help</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">help [-dms] [pattern ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">32</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">history</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">history [-c] [-d offset] [n] or history -anrw [filename]&gt;</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">33</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">if</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">if COMMANDS; then COMMANDS; [ elif COMMANDS; then COMMAN&gt;</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">34</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">jobs</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">jobs [-lnprs] [jobspec ...] or jobs -x command [args]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">35</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">kill</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">kill [-s sigspec | -n signum | -sigspec] pid | jobspec .&gt;</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">36</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">let</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">let arg [arg ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">37</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">local</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">local [option] name[=value] ...</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">38</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">logout</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">logout [n]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">39</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">mapfile</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">mapfile [-d delim] [-n count] [-O origin] [-s count] [-t&gt;</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">40</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">popd</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">popd [-n] [+N | -N]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">41</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">printf</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">printf [-v var] format [arguments]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">42</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">pushd</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">pushd [-n] [+N | -N | dir]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">43</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">pwd</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">pwd [-LP]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">44</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">read</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">read [-ers] [-a array] [-d delim] [-i text] [-n nchars] &gt;</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">45</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">readarray</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">readarray [-d delim] [-n count] [-O origin] [-s count] [&gt;</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">46</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">readonly</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">readonly [-aAf] [name[=value] ...] or readonly -p</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">47</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">return</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">return [n]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">48</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">select</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">select NAME [in WORDS ... ;] do COMMANDS; done</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">49</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">set</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">set [-abefhkmnptuvxBCHP] [-o option-name] [--] [arg ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">50</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">shift</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">shift [n]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">51</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">shopt</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">shopt [-pqsu] [-o] [optname ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">52</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">source</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">source filename [arguments]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">53</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">suspend</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">suspend [-f]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">54</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">test</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">test [expr]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">55</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">time</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">time [-p] pipeline</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">56</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">times</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">times</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">57</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">trap</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">trap [-lp] [[arg] signal_spec ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">58</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">true</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">true</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">59</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">type</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">type [-afptP] name [name ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">60</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">typeset</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">typeset [-aAfFgilnrtux] [-p] name[=value] ...</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">61</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">ulimit</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">ulimit [-SHabcdefiklmnpqrstuvxPT] [limit]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">62</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">umask</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">umask [-p] [-S] [mode]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">63</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">unalias</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">unalias [-a] name [name ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">64</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">unset</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">unset [-f] [-v] [-n] [name ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">65</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">until</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">until COMMANDS; do COMMANDS; done</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">66</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">variables</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">variables - Names and meanings of some shell variables</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">67</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">wait</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">wait [-fn] [id ...]</td> 
 </tr> 
 <tr> 
 <td style="border-color:#000000;text-align:center;vertical-align:middle;width:61px;">68</td> 
 <td style="border-color:#000000;vertical-align:middle;width:88px;">while</td> 
 <td style="border-color:#000000;vertical-align:middle;width:489px;">while COMMANDS; do COMMANDS; done</td> 
 </tr> 
 </tbody> 
</table>

注意，有些命令格式比较长的都被截短了，如bind, case 等命令最后显示的是 > 字符。

要想个办法，做一个比较完整的内部命令列表：

**1. 把上表第2列，写入一个文本文件**，比如 list.txt

**2. 用vi编写一段shell代码**，如 lists.sh

hann@HannYang:~$ cat lists.sh

#!/bin/bash
 
 # 指定文本文件路径
 file_path="list.txt"
 
 # 打开文本文件并遍历每一行
 while IFS= read -r line; do
 # 获取帮助信息并输出
 help -s "$line" >> commands.txt
 done < "$file_path"
 
 echo "done!"

**3. 执行**，遍历list.txt列出完整命令格式，写入列表文件 commands.txt

hann@HannYang:~$ bash lists.sh

**4. 列出所有命令格式**

hann@HannYang:~$ cat -n commands.txt  
1 alias: alias \[-p\] \[name\[=value\] ... \]  
2 bg: bg \[job\_spec ...\]  
3 bind: bind \[-lpsvPSVX\] \[-m keymap\] \[-f filename\] \[-q name\] \[-u name\] \[-r keyseq\] \[-x keyseq:shell-command\] \[keyseq:readline-function or readline-command\]  
4 break: break \[n\]  
5 builtin: builtin \[shell-builtin \[arg ...\]\]  
6 caller: caller \[expr\]  
7 case: case WORD in \[PATTERN \[| PATTERN\]...) COMMANDS ;;\]... esac  
8 cd: cd \[-L|\[-P \[-e\]\] \[-@\]\] \[dir\]  
9 command: command \[-pVv\] command \[arg ...\]  
10 compgen: compgen \[-abcdefgjksuv\] \[-o option\] \[-A action\] \[-G globpat\] \[-W wordlist\] \[-F function\] \[-C command\] \[-X filterpat\] \[-P prefix\] \[-S suffix\] \[word\]  
11 complete: complete \[-abcdefgjksuv\] \[-pr\] \[-DEI\] \[-o option\] \[-A action\] \[-G globpat\] \[-W wordlist\] \[-F function\] \[-C command\] \[-X filterpat\] \[-P prefix\] \[-S suffix\] \[name ...\]  
12 compopt: compopt \[-o|+o option\] \[-DEI\] \[name ...\]  
13 continue: continue \[n\]  
14 coproc: coproc \[NAME\] command \[redirections\]  
15 declare: declare \[-aAfFgilnrtux\] \[-p\] \[name\[=value\] ...\]  
16 dirs: dirs \[-clpv\] \[+N\] \[-N\]  
17 disown: disown \[-h\] \[-ar\] \[jobspec ... | pid ...\]  
18 echo: echo \[-neE\] \[arg ...\]  
19 enable: enable \[-a\] \[-dnps\] \[-f filename\] \[name ...\]  
20 eval: eval \[arg ...\]  
21 exec: exec \[-cl\] \[-a name\] \[command \[arguments ...\]\] \[redirection ...\]  
22 exit: exit \[n\]  
23 export: export \[-fn\] \[name\[=value\] ...\] or export -p  
24 false: false  
25 fc: fc \[-e ename\] \[-lnr\] \[first\] \[last\] or fc -s \[pat=rep\] \[command\]  
26 fg: fg \[job\_spec\]  
27 for: for NAME \[in WORDS ... \] ; do COMMANDS; done  
28 function: function name \{ COMMANDS ; \} or name () \{ COMMANDS ; \}  
29 getopts: getopts optstring name \[arg\]  
30 hash: hash \[-lr\] \[-p pathname\] \[-dt\] \[name ...\]  
31 help: help \[-dms\] \[pattern ...\]  
32 history: history \[-c\] \[-d offset\] \[n\] or history -anrw \[filename\] or history -ps arg \[arg...\]  
33 if: if COMMANDS; then COMMANDS; \[ elif COMMANDS; then COMMANDS; \]... \[ else COMMANDS; \] fi  
34 jobs: jobs \[-lnprs\] \[jobspec ...\] or jobs -x command \[args\]  
35 kill: kill \[-s sigspec | -n signum | -sigspec\] pid | jobspec ... or kill -l \[sigspec\]  
36 let: let arg \[arg ...\]  
37 local: local \[option\] name\[=value\] ...  
38 logout: logout \[n\]  
39 mapfile: mapfile \[-d delim\] \[-n count\] \[-O origin\] \[-s count\] \[-t\] \[-u fd\] \[-C callback\] \[-c quantum\] \[array\]  
40 popd: popd \[-n\] \[+N | -N\]  
41 printf: printf \[-v var\] format \[arguments\]  
42 pushd: pushd \[-n\] \[+N | -N | dir\]  
43 pwd: pwd \[-LP\]  
44 read: read \[-ers\] \[-a array\] \[-d delim\] \[-i text\] \[-n nchars\] \[-N nchars\] \[-p prompt\] \[-t timeout\] \[-u fd\] \[name ...\]  
45 readarray: readarray \[-d delim\] \[-n count\] \[-O origin\] \[-s count\] \[-t\] \[-u fd\] \[-C callback\] \[-c quantum\] \[array\]  
46 readonly: readonly \[-aAf\] \[name\[=value\] ...\] or readonly -p  
47 return: return \[n\]  
48 select: select NAME \[in WORDS ... ;\] do COMMANDS; done  
49 set: set \[-abefhkmnptuvxBCHP\] \[-o option-name\] \[--\] \[arg ...\]  
50 shift: shift \[n\]  
51 shopt: shopt \[-pqsu\] \[-o\] \[optname ...\]  
52 source: source filename \[arguments\]  
53 suspend: suspend \[-f\]  
54 test: test \[expr\]  
55 time: time \[-p\] pipeline  
56 times: times  
57 trap: trap \[-lp\] \[\[arg\] signal\_spec ...\]  
58 true: true  
59 type: type \[-afptP\] name \[name ...\]  
60 typeset: typeset \[-aAfFgilnrtux\] \[-p\] name\[=value\] ...  
61 ulimit: ulimit \[-SHabcdefiklmnpqrstuvxPT\] \[limit\]  
62 umask: umask \[-p\] \[-S\] \[mode\]  
63 unalias: unalias \[-a\] name \[name ...\]  
64 unset: unset \[-f\] \[-v\] \[-n\] \[name ...\]  
65 until: until COMMANDS; do COMMANDS; done  
66 variables: variables - Names and meanings of some shell variables  
67 wait: wait \[-fn\] \[id ...\]  
68 while: while COMMANDS; do COMMANDS; done

同样，代码中help的参数换成-d 就能得到命令的功能简介。

hann@HannYang:~$ cat lists.sh

#!/bin/bash
 
 # 指定文本文件路径
 file_path="list.txt"
 
 rm commands.txt
 
 # 打开文本文件并遍历每一行
 while IFS= read -r line; do
 # 获取帮助信息并输出
 help -d "$line" >> commands.txt
 done < "$file_path"
 
 echo "done!"

**5. 列出所有命令简介**

hann@HannYang:~$ cat -n commands.txt  
1 alias - Define or display aliases.  
2 bg - Move jobs to the background.  
3 bind - Set Readline key bindings and variables.  
4 break - Exit for, while, or until loops.  
5 builtin - Execute shell builtins.  
6 caller - Return the context of the current subroutine call.  
7 case - Execute commands based on pattern matching.  
8 cd - Change the shell working directory.  
9 command - Execute a simple command or display information about commands.  
10 compgen - Display possible completions depending on the options.  
11 complete - Specify how arguments are to be completed by Readline.  
12 compopt - Modify or display completion options.  
13 continue - Resume for, while, or until loops.  
14 coproc - Create a coprocess named NAME.  
15 declare - Set variable values and attributes.  
16 dirs - Display directory stack.  
17 disown - Remove jobs from current shell.  
18 echo - Write arguments to the standard output.  
19 enable - Enable and disable shell builtins.  
20 eval - Execute arguments as a shell command.  
21 exec - Replace the shell with the given command.  
22 exit - Exit the shell.  
23 export - Set export attribute for shell variables.  
24 false - Return an unsuccessful result.  
25 fc - Display or execute commands from the history list.  
26 fg - Move job to the foreground.  
27 for - Execute commands for each member in a list.  
28 function - Define shell function.  
29 getopts - Parse option arguments.  
30 hash - Remember or display program locations.  
31 help - Display information about builtin commands.  
32 history - Display or manipulate the history list.  
33 if - Execute commands based on conditional.  
34 jobs - Display status of jobs.  
35 kill - Send a signal to a job.  
36 let - Evaluate arithmetic expressions.  
37 local - Define local variables.  
38 logout - Exit a login shell.  
39 mapfile - Read lines from the standard input into an indexed array variable.  
40 popd - Remove directories from stack.  
41 printf - Formats and prints ARGUMENTS under control of the FORMAT.  
42 pushd - Add directories to stack.  
43 pwd - Print the name of the current working directory.  
44 read - Read a line from the standard input and split it into fields.  
45 readarray - Read lines from a file into an array variable.  
46 readonly - Mark shell variables as unchangeable.  
47 return - Return from a shell function.  
48 select - Select words from a list and execute commands.  
49 set - Set or unset values of shell options and positional parameters.  
50 shift - Shift positional parameters.  
51 shopt - Set and unset shell options.  
52 source - Execute commands from a file in the current shell.  
53 suspend - Suspend shell execution.  
54 test - Evaluate conditional expression.  
55 time - Report time consumed by pipeline's execution.  
56 times - Display process times.  
57 trap - Trap signals and other events.  
58 true - Return a successful result.  
59 type - Display information about command type.  
60 typeset - Set variable values and attributes.  
61 ulimit - Modify shell resource limits.  
62 umask - Display or set file mode mask.  
63 unalias - Remove each NAME from the list of defined aliases.  
64 unset - Unset values and attributes of shell variables and functions.  
65 until - Execute commands as long as a test does not succeed.  
66 variables - Common shell variable names and usage.  
67 wait - Wait for job completion and return exit status.  
68 while - Execute commands as long as a test succeeds.

**简单翻译：**

1 alias-定义或显示别名。

2 bg-将作业移到后台。

3 bind-设置Readline键绑定和变量。

4 break-退出循环、while或直到循环。

5 builtin-执行shell内建。

6 caller-返回当前子例程调用的上下文。

7 case-基于模式匹配执行命令。

8 cd-更改shell工作目录。

9 command-执行一个简单的命令或显示有关命令的信息。

10 compgen-根据选项显示可能的完成情况。

11 complete-指定Readline如何完成参数。