？keyword:以keyword指定的字符串为关键字，从当前界面所在位置向文件首部搜索；不区分字符大小写
n:跟收缩命令同方向，下一个 N:跟搜索命令反向，上一个
当不看man手册时q为退出
man的实际应用
下面通过一个实际的问题，来说明man的作用
例子：字符终端登陆时，显示当前登陆终端号，主机名和当前时间。
要求使用man查找实现上述要求，提示:修改/etc/issue文件。怎么修改可以通过man查看issue求助。
我们先用cat看下/etc/issue文件
# cat /etc/issue
CentOS release 6.8 (Final)
Kernel \r on an \m
之后我们
man issue
Formatting page, please wait...
ISSUE(5) Linux Programmer’s Manual ISSUE(5)
NAME
issue - pre-login message and identification file
DESCRIPTION
The file /etc/issue is a text file which contains a message or system
identification to be printed before the login prompt. It may contain
various @char and \char sequences, if supported by the getty-type pro-
gram employed on the system.
FILES
/etc/issue
SEE ALSO
motd(5), agetty(8), mingetty(8)
COLOPHON
This page is part of release 3.22 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at .
Linux 1993-07-24 ISSUE(5)
查看之后发现找不到一点有价值的信息，不过在最后提示我们可以查看motd、agetty、mingetty这三个文件。
man motd
MOTD(5) Linux Programmer’s Manual MOTD(5)
NAME
motd - message of the day
DESCRIPTION
The contents of /etc/motd are displayed by login(1) after a successful
login but just before it executes the login shell.
The abbreviation "motd" stands for "message of the day", and this file
has been traditionally used for exactly that (it requires much less
disk space than mail to all users).
FILES
/etc/motd
SEE ALSO
login(1), issue(5)
COLOPHON
This page is part of release 3.22 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at .
Linux 1992-12-29 MOTD(5)
motd里面也没有值得我们参考的信息，继续下一个
man agentty
AGETTY(8) AGETTY(8)
NAME
agetty - alternative Linux getty
SYNOPSIS
agetty [-8ihLmnUw] [-f issue_file] [-l login_program] [-I init] [-t
timeout] [-H login_host] port baud_rate,... [term]
agetty [-8ihLmnw] [-f issue_file] [-l login_program] [-I init] [-t
timeout] [-H login_host] baud_rate,... port [term]
DESCRIPTION
agetty opens a tty port, prompts for a login name and invokes the
/bin/login command. It is normally invoked by init(8).
agetty has several non-standard features that are useful for hard-wired
and for dial-in lines:
o Adapts the tty settings to parity bits and to erase, kill, end-
of-line and uppercase characters when it reads a login name.
The program can handle 7-bit characters with even, odd, none or
space parity, and 8-bit characters with no parity. The following
special characters are recognized: @ and Control-U (kill); #,
DEL and back space (erase); carriage return and line feed (end
of line). See also --erase-chars and --kill-chars options.
o Optionally deduces the baud rate from the CONNECT messages pro-
duced by Hayes(tm)-compatible modems.
...
..
.