linux中的帮助命令

Z时代
2024-01-10
分类：综合

# 查看ls命令的帮助信息 man ls 空格下翻页 pageup 上翻页上箭头向上下箭头向下 /关键字搜索(回车搜索,n往下找) # 查看/etc/services配置文件帮助文档 man services 提示No manual entry for services 运行命令yum -y install man-pages,然后就可以运行了 # 查看/etc/passwd配置文件的帮助文档(不正确) man passwd 查询出来的命令的帮助文档,此时是不对的 whereis passwd [root@izm5e2q95pbpe1hh0kkwoiz ~]# whereis passwd passwd: /usr/bin/passwd /etc/passwd /usr/share/man/man1/passwd.1.gz /usr/share/man/man5/passwd.5.gz passwd既有命令又有配置文件,优先显示命令的帮助文档 1 命令的帮助文档 5 配置文件的帮助文档 # 查看passwd配置文件的帮助文档

man 5 passwd

whatis

查看命令的简单的描述信息

示例

# 查看ls的简单的描述信息
whatis ls
[root@izm5e2q95pbpe1hh0kkwoiz ~]# whatis lsls (1)               - list directory contents

apropos

查看配置文件的简单的描述信息

示例

# 查看services的简单描述信息

apropos services

--help

查看某个具体命令的选项信息

示例

# 查看touch命令的具体选项信息 touch --help [root@izm5e2q95pbpe1hh0kkwoiz ~]# touch --help Usage: touch [OPTION]... FILE... Update the access and modification times of each FILE to the current time. A FILE argument that does not exist is created empty, unless -c or -h is supplied. A FILE argument string of - is handled specially and causes touch to change the times of the file associated with standard output. Mandatory arguments to long options are mandatory for short options too. -a change only the access time -c, --no-create do not create any files -d, --date=STRING parse STRING and use it instead of current time -f (ignored) -h, --no-dereference affect each symbolic link instead of any referenced file (useful only on systems that can change the timestamps of a symlink) -m change only the modification time -r, --reference=FILE use this file's times instead of current time -t STAMP use [[CC]YY]MMDDhhmm[.ss] instead of current time --time=WORD change the specified time: WORD is access, atime, or use: equivalent to -a WORD is modify or mtime: equivalent to -m --help display this help and exit --version output version information and exit Note that the -d and -t options accept different time-date formats. GNU coreutils online help: <http://www.gnu.org/software/coreutils/> For complete documentation, run: info coreutils 'touch invocation'

info

使用方法跟man 几乎一致, 显示的信息也大同小异

help

解释

命令名称:help 命令所在路径:shell内置命令(无法通过which查找路径,无法通过man查看帮助文档) 执行权限:所有用户

功能描述:获得shell内置命令的帮助信息

语法

help [命令]

示例

# 使用man查看shell内置命令(无法查看正确的帮助信息) man cd NAME bash, :, ., [, alias, bg, bind, break, builtin, caller, cd, command, compgen, complete, compopt, continue, declare, dirs, disown, echo, enable, eval, exec, exit, export, false, fc, fg, getopts, hash, help, history, jobs, kill, let, local, logout, mapfile, popd, printf, pushd, pwd, read, readonly, return, set, shift, shopt, source, suspend, test, times, trap, true, type, typeset, ulimit, umask, unalias, unset, wait - bash built-in commands, see bash(1) ...... # man 查询cd查不出来正确的帮助文档信息,相反查出来的是shell的内置命令 # 正确查看shell内置命令的帮助文档信息,查看umask help umask [root@izm5e2q95pbpe1hh0kkwoiz ~]# help umask umask: umask [-p] [-S] [mode] Display or set file mode mask. Sets the user file-creation mask to MODE. If MODE is omitted, prints the current value of the mask. If MODE begins with a digit, it is interpreted as an octal number; otherwise it is a symbolic mode string like that accepted by chmod(1). Options: -p if MODE is omitted, output in a form that may be reused as input -S makes the output symbolic; otherwise an octal number is output Exit Status: Returns success unless MODE is invalid or an invalid option is given.

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