man命令--Linux命令应用大词典729个命令解读

内容来源于人民邮电出版社《Linux命令应用大词典》

讲述729个命令，1935个例子

学习Linux系统的参考书、案头书，遇到不懂的命令或命令选项一查即可争取每天都发布内容本文出自 “airfish2000” 博客，更多命令查看博客：http://airfish2000.blog.51cto.com/10829608/1881635

man命令使用man命令可以格式化并显示在线的手册页。man会列出一份完整的说明，其内容包括命令语法、各选项的意义以及相关命令等。命令语法：man [选项] [名称]命令中各选项的含义如表所示。表 man命令选项含义

选项	含义
-M <路径>	指定man手册页的搜索路径
-a	显示所有的手册页，而不是只显示第一个
-d	主要用于检查，如果用户加入了一个新的文件，就可以用这个选项检查是否出错，这个选项并不会列出文件内容
-f	只显示出命令的功能而不显示详细的说明文件，和whatis命令一样功能
-p	字符串设定运行的预先处理程序的顺序
-w	不显示手册页内容，只显示将被格式化和显示的文件所在位置

例：显示pwd命令的man手册页。[root@rhel~]# man pwdPWD(1) User Commands PWD(1) NAME pwd - print name of current/workingdirectory SYNOPSIS pwd [OPTION]... DESCRIPTION Print the full filename of the currentworking directory. -L, --logical use PWD from environment, even ifit contains symlinks -P, --physical avoid all symlinks --help display this help and exit --version output version information andexit NOTE: your shell may have its own version of pwd, whichusually supersedes the version described here. Please refer to your shell’s documentation fordetails about the options it supports. AUTHOR Written by Jim Meyering. REPORTINGBUGS Report pwd bugs to bug-coreutils@gnu.org GNU coreutils home page:<http://www.gnu.org/software/coreutils/> General help using GNU software:<http://www.gnu.org/gethelp/> Report pwd translation bugs to<http://translationproject.org/team/> COPYRIGHT Copyright 2010 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>. This is free software: you are free tochange and redistribute it. There is NOWARRANTY, to the extent permitted by law. SEEALSO getcwd(3) The full documentation for pwd ismaintained as a Texinfo manual. If theinfo and pwd programs are properly installed at your site, the command info coreutils 'pwd invocation' should give you access to the completemanual. GNUcoreutils 8.4 April2012 PWD(1)//可以按[q]键退出man手册页例：查看/etc/passwd文件的man手册页。[root@rhel ~]# man 5 passwdPASSWD(5) Linux Programmer’s Manual PASSWD(5) NAME passwd -password file DESCRIPTION Passwd is a text file, that contains a list of thesystem’s accounts, giving for each account some useful infor- mation likeuser ID, group ID, home directory, shell, etc. Often, it also contains the encrypted passwords for eachaccount. It should have general readpermission (many utilities, like ls(1) use it to map user IDs to user- names), butwrite access only for the superuser. In the goodold days there was no great problem with this general read permission. Everybody could read the encrypted passwords, but the hardware was too slow to crack a well-chosen password, andmoreover, the basic assumptionused to be that of a friendly user-community. These days many people run some version of the shadow password suite, where /etc/passwd has "x" instead of encrypted passwords, and the encrypted passwordsare in /etc/shadowwhich is readable by the superuser only. If theencrypted password, whether in /etc/passwd or in /etc/shadow, is an emptystring, login is allowed without even asking for a password. Note that this functionality may beintentionally disabled in applications, or con- figurable (forexample using the "nullok" or "nonull" arguments topam_unix.so).........................（省略）例：显示passwd命令和/etc/passwd文件手册页所在位置。[root@rhel ~]# man -w passwd/usr/share/man/man1/passwd.1.gz[root@rhel ~]# man -w5 passwd/usr/share/man/man5/passwd.5.gz