9.2-grep命令(中)

-n 'root' 过滤出带有某个关键词的行，并输出行号

[[e-mail] grep]# grep -n 'root' passwd
1:root:x:0:0:root:/root:/bin/bash
10:operator:x:11:0:operator:/root:/sbin/nologin
[[e-mail] grep]# 

-nv 'nologin' 过滤出不带有某个关键词的行，并输出行号

[[e-mail] grep]# grep -nv 'nologin' passwd
1:root:x:0:0:root:/root:/bin/bash
2:bin:x:1:1:bin:/bin:/sbin/NOLogin
6:sync:x:5:0:sync:/sbin:/bin/sync
7:shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
8:halt:x:7:0:halt:/sbin:/sbin/halt
20:evan1:x:1000:1000::/home/evan1:/bin/bash
21:evan2:x:1001:1001::/home/evan2:/bin/bash
22:user1:x:1002:1002::/home/user1:/bin/bash
23:user2:x:1004:1005::/home/user2:/bin/bash
25:user4:x:1007:1007::/home/user4:/bin/bash
[[e-mail] grep]#

-n '[0-9]' 过滤出所有包含数字的行，并输出行号

[[e-mail] grep]# grep -n '[0-9]' /etc/inittab
9:# multi-user.target: analogous to runlevel 3
10:# graphical.target: analogous to runlevel 5
[[e-mail] grep]#

-nv '[0-9]' 过滤出所有不包含数字的行，并输出行号

[[e-mail] grep]# grep -nv '[0-9]' /etc/inittab
1:# inittab is no longer used when using systemd.
2:#
3:# ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
4:#
5:# Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target
6:#
7:# systemd uses 'targets' instead of runlevels. By default, there are two main targets:
8:#
11:#
12:# To view current default target, run:
13:# systemctl get-default
14:#
15:# To set a default target, run:
16:# systemctl set-default TARGET.target
17:#
[[e-mail] grep]# 

可以看到第9和第10行没有了

-n '^#' 过滤出所有以 # 开头的行，并输出行号
查看以 # 开头的行，并输出行号

[[e-mail] grep]# grep -n '^#' /etc/inittab
1:# inittab is no longer used when using systemd.
2:#
3:# ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
4:#
5:# Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target
6:#
7:# systemd uses 'targets' instead of runlevels. By default, there are two main targets:
8:#
9:# multi-user.target: analogous to runlevel 3
10:# graphical.target: analogous to runlevel 5
11:#
12:# To view current default target, run:
13:# systemctl get-default
14:#
15:# To set a default target, run:
16:# systemctl set-default TARGET.target
17:#
[[e-mail] grep]#

我们发现这个文件所有行中都有 # ，接下来，我们 cp 一份这个文件，然后对它进行一下编辑

[[e-mail] grep]# cp /etc/inittab .
[[e-mail] grep]# ls
inittab  passwd
[[e-mail] grep]# vi inittab

手动添加一行，并保存退出。

[[e-mail] grep]# grep -n '^#' /etc/inittab
1:# inittab is no longer used when using systemd.
2:#
3:# ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
4:#
5:# Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target
6:#
7:# systemd uses 'targets' instead of runlevels. By default, there are two main targets:
8:#
9:# multi-user.target: analogous to runlevel 3
10:# graphical.target: analogous to runlevel 5
11:#
12:# To view current default target, run:
13:# systemctl get-default
14:#
15:# To set a default target, run:
16:# systemctl set-default TARGET.target
17:#
[[e-mail] grep]#

我们发现，我们最后添加的那行是没有展示的

过滤掉以 # 开头的行，并输出行号

[[e-mail] grep]# grep -nv '^#' inittab
18:ahcbabvjjs3761738183
[[e-mail] grep]# 

过滤掉所有空行和以 # 开头的行

[[e-mail] grep]# grep -v '^#' inittab | grep -v '^$'
ahcbabvjjs3761738183
[[e-mail] grep]# 

[^0-9] 匹配非方括号里面的内容
[^] 匹配非方括号里面的内容。就是：只要不是方括号里面的内容都打印出来。
把非数字的内容呈现出来

[[e-mail] grep]# grep '[^0-9]' inittab

符合条件的字符均已加粗，只有数字没变粗，表明没筛选没有符合条件

^[^0-9] 匹配非方括号里面的内容开头的所有字符
^[^] 匹配非方括号里面的内容开头的所有字符。 只要不是方括号里面的内容所开头的，都打印出来。
把非数字开头的内容呈现出来

[[e-mail] grep]# grep '^[^0-9]' inittab

符合条件的字符均已加粗