Linux命令(126)之help

linux命令之help

1.help介绍

linux命令help用来显示内置命令的帮助信息

2.help用法

help [参数] command

|----|------------------|
| 参数 | 说明 |
| -d | 输出每个命令的简短描述 |
| -m | 以手册页格式显示命令用法 |
| -s | 仅输出每个匹配命令的简短使用概要 |
[help参数]

3.实例

3.1.以手册页格式显示命令用法

命令:

help -m

复制代码
[root@rhel77 ~]# help -m
GNU bash, version 4.2.46(2)-release (x86_64-redhat-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 [file>
 (( expression ))                                       if COMMANDS; then COMMANDS; [ elif COMMANDS; then C>
 . filename [arguments]                                 jobs [-lnprs] [jobspec ...] or jobs -x command [arg>
 :                                                      kill [-s sigspec | -n signum | -sigspec] pid | jobs>
 [ arg... ]                                             let arg [arg ...]
 [[ expression ]]                                       local [option] name[=value] ...
 alias [-p] [name[=value] ... ]                         logout [n]
 bg [job_spec ...]                                      mapfile [-n count] [-O origin] [-s count] [-t] [-u >
 bind [-lpvsPVS] [-m keymap] [-f filename] [-q name] >  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 ;;]..>  read [-ers] [-a array] [-d delim] [-i text] [-n nch>
 cd [-L|[-P [-e]]] [dir]                                readarray [-n count] [-O origin] [-s count] [-t] [->
 command [-pVv] command [arg ...]                       readonly [-aAf] [name[=value] ...] or readonly -p
 compgen [-abcdefgjksuv] [-o option]  [-A action] [-G>  return [n]
 complete [-abcdefgjksuv] [-pr] [-DE] [-o option] [-A>  select NAME [in WORDS ... ;] do COMMANDS; done
 compopt [-o|+o option] [-DE] [name ...]                set [-abefhkmnptuvxBCHP] [-o option-name] [--] [arg>
 continue [n]                                           shift [n]
 coproc [NAME] command [redirections]                   shopt [-pqsu] [-o] [optname ...]
 declare [-aAfFgilrtux] [-p] [name[=value] ...]         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] [name ...]           times
 eval [arg ...]                                         trap [-lp] [[arg] signal_spec ...]
 exec [-cl] [-a name] [command [arguments ...]] [redi>  true
 exit [n]                                               type [-afptP] name [name ...]
 export [-fn] [name[=value] ...] or export -p           typeset [-aAfFgilrtux] [-p] name[=value] ...
 false                                                  ulimit [-SHacdefilmnpqrstuvx] [limit]
 fc [-e ename] [-lnr] [first] [last] or fc -s [pat=re>  umask [-p] [-S] [mode]
 fg [job_spec]                                          unalias [-a] name [name ...]
 for NAME [in WORDS ... ] ; do COMMANDS; done           unset [-f] [-v] [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 variab>
 getopts optstring name [arg]                           wait [id]
 hash [-lr] [-p pathname] [-dt] [name ...]              while COMMANDS; do COMMANDS; done
 help [-dms] [pattern ...]                              { COMMANDS ; }
[root@rhel77 ~]# 

3.2.输出内置命令的简短描述

命令:

help -d fg

复制代码
[root@rhel77 ~]# help -d fg
fg - Move job to the foreground.
[root@rhel77 ~]# 

3.3.仅输出内置命令的简短使用概要

命令:

help -s fg

复制代码
[root@rhel77 ~]# help -s fg
fg: fg [job_spec]
[root@rhel77 ~]# 

3.4.显示help命令的用法

命令:

help help

复制代码
[root@rhel77 ~]# help help
help: help [-dms] [pattern ...]
    Display information about builtin commands.
    
    Displays brief summaries of builtin commands.  If PATTERN is
    specified, gives detailed help on all commands matching PATTERN,
    otherwise the list of help topics is printed.
    
    Options:
      -d	output short description for each topic
      -m	display usage in pseudo-manpage format
      -s	output only a short usage synopsis for each topic matching
    	PATTERN
    
    Arguments:
      PATTERN	Pattern specifiying a help topic
    
    Exit Status:
    Returns success unless PATTERN is not found or an invalid option is given.
[root@rhel77 ~]# 
相关推荐
tb_first31 分钟前
Linux入门1(2/2)
linux
cellurw1 小时前
Day72 传感器分类、关键参数、工作原理与Linux驱动开发(GPIO/I²C/Platform/Misc框架)
linux·c语言·驱动开发
NextZeros1 小时前
基于CentOS安装LNMP
linux·centos
梁萌1 小时前
Linux安装mysql8.4.6
linux·运维·mysql安装·8.4.6
gtr20201 小时前
Ubuntu24.04 无法读取 U盘
linux
南棱笑笑生1 小时前
20251028在Ubuntu20.04.6上编译AIO-3576Q38开发板的Buildroot系统
大数据·linux·服务器·rockchip
FreeBuf_1 小时前
Ubuntu内核曝严重UAF漏洞,可致攻击者获取Root权限
linux·运维·ubuntu
Jason_zhao_MR1 小时前
RK3576机器人核心:三屏异显+八路摄像头,重塑机器人交互与感知
linux·人工智能·嵌入式硬件·计算机视觉·机器人·嵌入式·交互
☆璇1 小时前
【Linux】数据链路层
linux·服务器·网络
初学者_xuan3 小时前
零基础新手小白快速了解掌握服务集群与自动化运维(十六)集群部署模块——Keepalived双机热备
运维·自动化·github