• man 获得帮助信息

    一、使用man工具

    1.man机制概述

    Linux提供的一种集中手册页文档机制

    −大多数程序/配置文件/库函数都提供手册页

    −包括命令名称、语法、用途描述、选项、作者等信息

    −通过统一阅读工具man来获得这些帮助

    2.使用man帮助工具

     3.练习

    查阅uname命令的man手册页，解释其格式及常见选项

    1. [root@hadoop ~]# man uname
    2.  
    3. UNAME(1)                         User Commands                        UNAME(1)
    4.  
    5. NAME
    6.        uname - print system information
    7.  
    8. SYNOPSIS
    9.        uname [OPTION]...
    10.  
    11. DESCRIPTION
    12.        Print certain system information.  With no OPTION, same as -s.
    13.  
    14.        -a, --all
    15.               print all information, in the following order, except omit -p and -i if unknown:
    16.  
    17.        -s, --kernel-name
    18.               print the kernel name
    19.  
    20.        -n, --nodename
    21.               print the network node hostname
    22.  
    23.        -r, --kernel-release
    24.               print the kernel release
    25.  
    26.        -v, --kernel-version
    27.               print the kernel version
    28.  
    29.        -m, --machine
    30.               print the machine hardware name
    31.  
    32.        -p, --processor
    33.               print the processor type or "unknown"
    34.  
    35.        -i, --hardware-platform
    36.               print the hardware platform or "unknown"
    37.  
    38.        -o, --operating-system
    39.               print the operating system
    40.  
    41.        --help display this help and exit
    42.  
    43.        --version
    44.               output version information and exit
    45.  
    46. AUTHOR
    47.        Written by David MacKenzie.
    48.  
    49. REPORTING BUGS
    50.        Report uname bugs to bug-coreutils@gnu.org
    51.        GNU coreutils home page: <http://www.gnu.org/software/coreutils/>
    52.        General help using GNU software: <http://www.gnu.org/gethelp/>
    53.        Report uname translation bugs to <http://translationproject.org/team/>
    54.  
    55. COPYRIGHT
    56.        Copyright  ©  2010  Free  Software  Foundation,  Inc.   License  GPLv3+:  GNU  GPL version 3 or later
    57.        <http://gnu.org/licenses/gpl.html>.
    58.        This is free software: you are free to change and redistribute it.  There  is  NO  WARRANTY,  to  the
    59.        extent permitted by law.
    60.  
    61. SEE ALSO
    62.        arch(1), uname(2)
    63.  
    64.        The  full  documentation for uname is maintained as a Texinfo manual.  If the info and uname programs
    65.        are properly installed at your site, the command
    66.  
    67.               info coreutils 'uname invocation'
    68.  
    69.        should give you access to the complete manual.
    70.  
    71. GNU coreutils 8.4                November 2013                        UNAME(1)

    查阅shutdown命令的man手册页，解释其格式及常见选项

    1. [root@hadoop ~]# man shutdown
    2.  
    3. shutdown(8)                                                        shutdown(8)
    4.  
    5. NAME
    6.        shutdown - bring the system down
    7.  
    8. SYNOPSIS
    9.        shutdown [OPTION]...  TIME [MESSAGE]
    10.  
    11. DESCRIPTION
    12.        shutdown  arranges for the system to be brought down in a safe way.  All logged-in users are notified
    13.        that the system is going down and, within the last five minutes of TIME, new logins are prevented.
    14.  
    15.        TIME may have different formats, the most common is simply the word ’now’ which will bring the system
    16.        down  immediately.   Other valid formats are +m, where m is the number of minutes to wait until shut-
    17.        ting down and hh:mm which specifies the time on the 24hr clock.
    18.  
    19.        Once TIME has elapsed, shutdown sends a request to the init(8) daemon to bring the system  down  into
    20.        the appropriate runlevel.
    21.  
    22.        This  is performed by emitting the runlevel(7) event, which includes the new runlevel in the RUNLEVEL
    23.        environment variable as well as  the  previous  runlevel  (obtained  from  the  environment  or  from
    24.        /var/run/utmp)  in  the  PREVLEVEL  variable.  An additional INIT_HALT variable may be set, this will
    25.        contain the value HALT when bringing the system down for halt and POWEROFF when bringing  the  system
    26.        down for power off.
    27.  
    28. OPTIONS
    29.        -r     Requests that the system be rebooted after it has been brought down.
    30.  
    31.        -h     Requests  that the system be either halted or powered off after it has been brought down, with
    32.               the choice as to which left up to the system.
    33.  
    34.        -H     Requests that the system be halted after it has been brought down.
    35.  
    36.        -P     Requests that the system be powered off after it has been brought down.
    37.  
    38.        -c     Cancels a running shutdown.  TIME is not specified with this option,  the  first  argument  is
    39.               MESSAGE.
    40.  
    41.        -k     Only  send out the warning messages and disable logins, do not actually bring the system down.
    42.  
    43. ENVIRONMENT
    44.        RUNLEVEL
    45.               shutdown will read the current runlevel from this environment variable if set in preference to
    46.               reading from /var/run/utmp
    47.  
    48. FILES
    49.        /var/run/utmp
    50.               Where the current runlevel will be read from; this file will also be updated with the new run-
    51.               level.
    52.  
    53.        /var/log/wtmp
    54.               A new runlevel record will be appended to this file for the new runlevel.
    55.  
    56. NOTES
    57.        The Upstart init(8) daemon does not keep track of runlevels  itself,  instead  they  are  implemented
    58.        entirely by its userspace tools.
    59.  
    60.        See runlevel(7) for more details.
    61.  
    62. AUTHOR
    63.        Written by Scott James Remnant <scott@netsplit.com>
    64.  
    65. REPORTING BUGS
    66.        Report bugs at <https://launchpad.net/upstart/+bugs>
    67.  
    68. COPYRIGHT
    69.        Copyright © 2009 Canonical Ltd.
    70.        This  is  free  software;  see the source for copying conditions.  There is NO warranty; not even for
    71.        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
    72.  
    73. SEE ALSO
    74.        runlevel(7) init(8) telinit(8) reboot(8)
    75.  
    76. Upstart                           2009-07-09                       shutdown(8)

    二、man手册页的分节

    1.man手册存放位置

    标准manual手册文档集中存放

    −/usr/share/share/man/.. .. 目录

    −/usr/share/share/man/zh_CN/.. ..

    1. [root@hadoop ~]# manpath
    2. /usr/local/share/man:/usr/share/man/en:/usr/share/man:/usr/soft/jdk/man:/usr/soft/scala/man

    2.分节机制及入口

    man分节入口

    1用户指令、2 系统、3 程序库、4 设备、5文件系统、6 游戏、7 杂项、8 系统指令、9 内核指令

    1和8的区别在于权限，1是普通用户，8是管理员

    选择指定的入口：man 节号手册名称

    1. [root@hadoop ~]# man ls
    2. LS(1)                            User Commands                           LS(1)
    3. #普通用户
    1. [root@hadoop ~]# man shutdown
    2. shutdown(8)                                                        shutdown(8)
    3. #管理员

    3.练习

     查阅命令程序passwd的手册页信息

    [root@hadoop ~]# man passwd

    查阅配置文件/etc/passwd的手册页信息

    [root@hadoop ~]# man 5 passwd

    三、whatis手册索引

    1.创建whatis数据库

    使用makewhatis工具

     [root@hadoop ~]# makewhatis//耐心等待执行完毕

    2.查询手册列表

    使用whatis工具

    用法：whatis手册名称

    1. [root@hadoop ~]# whatis passwd
    2. passwd               (1)  - update user's authentication tokens
    3. passwd [sslpasswd]   (1ssl)  - compute password hashes

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  • 原文地址：https://blog.csdn.net/m0_55834564/article/details/126304182