Linux常用命令系列——线上查询及帮助命令(help)

2018-02-07 20:13:08来源:cnblogs.com作者:阡陌·凉笙人点击

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文章目录:

    • 1.语法
    • 2.选项
    • 3.参数
    • 4.实例
    • 4.1 获取内置命令帮助信息
    • 4.2 获取外置命令帮助信息

help命令

        help命令用于显示shell内部命令的帮助信息。

1.语法

        help [选项] [参数]

2.选项

    • -s:输出短格式的帮助信息。仅包括命令格式。

3.参数

    • 内部命令:指定需要显示帮助信息的shell内部命令。

4.实例

4.1 获取内置命令帮助信息

[root@localhost ~]# help cdcd: cd [-L|-P] [dir]    Change the shell working directory.        Change the current directory to DIR.  The default DIR is the value of the    HOME shell variable.        The variable CDPATH defines the search path for the directory containing    DIR.  Alternative directory names in CDPATH are separated by a colon (:).    A null directory name is the same as the current directory.  If DIR begins    with a slash (/), then CDPATH is not used.        If the directory is not found, and the shell option `cdable_vars' is set,    the word is assumed to be  a variable name.  If that variable has a value,    its value is used for DIR.        Options:        -L    force symbolic links to be followed        -P    use the physical directory structure without following symbolic        links        The default is to follow symbolic links, as if `-L' were specified.        Exit Status:    Returns 0 if the directory is changed; non-zero otherwise.

4.2 获取外置命令帮助信息

[root@localhost ~]# mv --helpUsage: mv [OPTION]... [-T] SOURCE DEST  or:  mv [OPTION]... SOURCE... DIRECTORY  or:  mv [OPTION]... -t DIRECTORY SOURCE...Rename SOURCE to DEST, or move SOURCE(s) to DIRECTORY.Mandatory arguments to long options are mandatory for short options too.      --backup[=CONTROL]       make a backup of each existing destination file  -b                           like --backup but does not accept an argument  -f, --force                  do not prompt before overwriting  -i, --interactive            prompt before overwrite  -n, --no-clobber             do not overwrite an existing fileIf you specify more than one of -i, -f, -n, only the final one takes effect.      --strip-trailing-slashes  remove any trailing slashes from each SOURCE                                 argument  -S, --suffix=SUFFIX          override the usual backup suffix  -t, --target-directory=DIRECTORY  move all SOURCE arguments into DIRECTORY  -T, --no-target-directory    treat DEST as a normal file  -u, --update                 move only when the SOURCE file is newer                                 than the destination file or when the                                 destination file is missing  -v, --verbose                explain what is being done      --help     display this help and exit      --version  output version information and exitThe backup suffix is `~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX.The version control method may be selected via the --backup option or throughthe VERSION_CONTROL environment variable.  Here are the values:  none, off       never make backups (even if --backup is given)  numbered, t     make numbered backups  existing, nil   numbered if numbered backups exist, simple otherwise  simple, never   always make simple backupsReport mv bugs to bug-coreutils@gnu.orgGNU coreutils home page: <http://www.gnu.org/software/coreutils/>General help using GNU software: <http://www.gnu.org/gethelp/>For complete documentation, run: info coreutils 'mv invocation'

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