正则介绍及grep/egrep用法

​10月16日任务

9.1 正则介绍_grep上

9.2 grep中

9.3 grep下

扩展

把一个目录下，过滤全部*.php文档中含有eval的行

grep -r --include="*.php" 'eval' /data

 

9.1 正则介绍_grep上

什么是正则

• 正则就是一串有规律的字符串

• 掌握好正则对于编写shell脚本有很大帮助

• 各类编程语言中都有正则，原理是同样的

• 本章将要学习grep/egrep、sed 、awk   三剑客

#Cent OS 7.0如下的版本grep和egrep是不带颜色显示的，须要手动添加alias。

[root@centos6 ~]# vim .bashrc 
[root@centos6 ~]# . .bashrc 
[root@centos6 ~]# which egrep
alias egrep='egrep --color=auto'
    /bin/egrep
[root@centos6 ~]# which grep
alias grep='grep --color=auto'
    /bin/grep

 

grep

• grep [-cinvABC] 'word' filename

• -c    行数

• -i     不区分大小写

• -n     显示行号

• -v     取反

• -r     遍历全部子目录

• -A   后面跟数字，过滤出符合要求的行以及下边的n行

• -B     同上，过滤出符合要求的行以及上边的n行

• -C     同上，同时过滤出符合要求的行以及上下各n行

 

[root@centos6 ~]# which grep
alias grep='grep --color=auto'
    /bin/grep
[root@centos6 ~]# grep -c 'nologin' /etc/passwd
16
[root@centos6 ~]# grep -n 'nologin' /etc/passwd
2:bin:x:1:1:bin:/bin:/sbin/nologin
3:daemon:x:2:2:daemon:/sbin:/sbin/nologin
4:adm:x:3:4:adm:/var/adm:/sbin/nologin
5:lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
9:mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
10:uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin
11:operator:x:11:0:operator:/root:/sbin/nologin
12:games:x:12:100:games:/usr/games:/sbin/nologin
13:gopher:x:13:30:gopher:/var/gopher:/sbin/nologin
14:ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
15:nobody:x:99:99:Nobody:/:/sbin/nologin
16:vcsa:x:69:69:virtual console memory owner:/dev:/sbin/nologin
17:saslauth:x:499:76:Saslauthd user:/var/empty/saslauth:/sbin/nologin
18:postfix:x:89:89::/var/spool/postfix:/sbin/nologin
19:sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
20:ntp:x:38:38::/etc/ntp:/sbin/nologin
[root@centos6 ~]# grep -nv 'nologin' /etc/passwd
1:root:x:0:0:root:/root:/bin/bash
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
[root@centos6 ~]# grep -B2 'root' /etc/passwd
root:x:0:0:root:/root:/bin/bash
--
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
[root@centos6 ~]# grep -A2 'root' /etc/passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
--
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
gopher:x:13:30:gopher:/var/gopher:/sbin/nologin
[root@centos6 ~]# grep -C1 'root' /etc/passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
--
uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin

9.二、grep (中)

grep/egrep示例

• grep -n 'root' /etc/passwd

• grep -nv 'nologin'   /etc/passwd

• grep '[0-9]' /etc/inittab

• grep -v '[0-9]'  /etc/inittab

• grep -v '^#' /etc/inittab

• grep -v '^#' /etc/inittab -v '^$'

• grep '^[^a-zA-Z]'  text.txt             # ^在方括号外表示以什么开头，在方括号内表示取非

• grep 'r.o' test.txt                           # .表示一个字符

• grep 'oo*' test.txt                          # *表示*左边的字符重复0-n次

• grep '.*'    test.txt                          # .*表示匹配任意字符包括空行

• grep 'o\{2\}' /etc/passwd               # 特殊符号须要用脱意符号\，否则没法识别

• egrep 'o{2}' /etc/passwd                 # 用egrep命令，不须要脱意，｛｝表示前边字符的重复范围

• egrep 'o+' /etc/passwd                  # +表示+左边字符重复1-n次

• egrep 'oo?' /etc/passwd                 # ?表示？前边的字符重复0或者1次

• egrep 'root|nologin' /etc/passwd    # |表示或者

• egrep '(oo){2}'  /etc/passwd

[root@centos6 ~]# grep '[0-9]' passwd 
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
gopher:x:13:30:gopher:/var/gopher:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
vcsa:x:69:69:virtual console memory owner:/dev:/sbin/nologin
saslauth:x:499:76:Saslauthd user:/var/empty/saslauth:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
ntp:x:38:38::/etc/ntp:/sbin/nologin
[root@centos6 ~]# grep -v '[0-9]' passwd 
qwwwewer
[root@centos6 ~]# vim inittab 
[root@centos6 ~]# grep -nv '#' inittab 
26:aaaaaaaaaaaa
27:ashdfoaoiifuoa
28:111111111111111
30:id:3:initdefault:
[root@centos6 ~]# grep -v '#' inittab 
aaaaaaaaaaaa
ashdfoaoiifuoa
111111111111111
id:3:initdefault:
[root@centos6 ~]# grep -n '#' inittab 
1:# inittab is only used by upstart for the default runlevel.
2:#
3:# ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
4:#
5:# System initialization is started by /etc/init/rcS.conf
6:#
7:# Individual runlevels are started by /etc/init/rc.conf
8:#
9:# Ctrl-Alt-Delete is handled by /etc/init/control-alt-delete.conf
10:#
11:# Terminal gettys are handled by /etc/init/tty.conf and /etc/init/serial.conf,
12:# with configuration in /etc/sysconfig/init.
13:#
14:# For information on how to write upstart event handlers, or how
15:# upstart works, see init(5), init(8), and initctl(8).
16:#
17:# Default runlevel. The runlevels used are:
18:#   0 - halt (Do NOT set initdefault to this)
19:#   1 - Single user mode
20:#   2 - Multiuser, without NFS (The same as 3, if you do not have networking)
21:#   3 - Full multiuser mode
22:#   4 - unused
23:#   5 - X11
24:#   6 - reboot (Do NOT set initdefault to this)
25:# 
29:(&*&^$^$^#%#
[root@centos6 ~]# grep -n '^#' inittab 
1:# inittab is only used by upstart for the default runlevel.
2:#
3:# ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
4:#
5:# System initialization is started by /etc/init/rcS.conf
6:#
7:# Individual runlevels are started by /etc/init/rc.conf
8:#
9:# Ctrl-Alt-Delete is handled by /etc/init/control-alt-delete.conf
10:#
11:# Terminal gettys are handled by /etc/init/tty.conf and /etc/init/serial.conf,
12:# with configuration in /etc/sysconfig/init.
13:#
14:# For information on how to write upstart event handlers, or how
15:# upstart works, see init(5), init(8), and initctl(8).
16:#
17:# Default runlevel. The runlevels used are:
18:#   0 - halt (Do NOT set initdefault to this)
19:#   1 - Single user mode
20:#   2 - Multiuser, without NFS (The same as 3, if you do not have networking)
21:#   3 - Full multiuser mode
22:#   4 - unused
23:#   5 - X11
24:#   6 - reboot (Do NOT set initdefault to this)
25:# 
[root@centos6 ~]# grep -n '^[0-9]' inittab 
28:111111111111111
[root@centos6 ~]# grep -n '^[^0-9]' inittab 
1:# inittab is only used by upstart for the default runlevel.
2:#
3:# ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
4:#
5:# System initialization is started by /etc/init/rcS.conf
6:#
7:# Individual runlevels are started by /etc/init/rc.conf
8:#
9:# Ctrl-Alt-Delete is handled by /etc/init/control-alt-delete.conf
10:#
11:# Terminal gettys are handled by /etc/init/tty.conf and /etc/init/serial.conf,
12:# with configuration in /etc/sysconfig/init.
13:#
14:# For information on how to write upstart event handlers, or how
15:# upstart works, see init(5), init(8), and initctl(8).
16:#
17:# Default runlevel. The runlevels used are:
18:#   0 - halt (Do NOT set initdefault to this)
19:#   1 - Single user mode
20:#   2 - Multiuser, without NFS (The same as 3, if you do not have networking)
21:#   3 - Full multiuser mode
22:#   4 - unused
23:#   5 - X11
24:#   6 - reboot (Do NOT set initdefault to this)
25:# 
26:aaaaaaaaaaaa
27:ashdfoaoiifuoa
29:(&*&^$^$^#%#
30:id:3:initdefault:

 

9.三、grep(下)

[root@centos6 ~]# grep 'r.o' passwd 
root:x:0:0:root:/root:/bin/bash
ahkdhfa:r>oo:dfsa:13243
operator:x:11:0:operator:/root:/sbin/nologin

[root@centos6 ~]# grep 'ntp.*nologin' passwd        #匹配以ntp开头，nologin结束的行
ntp:x:38:38::/etc/ntp:/sbin/nologin
[root@centos6 ~]# grep '{2}' passwd             #错误示范
[root@centos6 ~]# grep 'o{2}' passwd           #错误示范
[root@centos6 ~]# grep 'o\{2\}' passwd           # {}须要加脱意符号\
root:x:0:0:root:/root:/bin/bash
ahkdhfa:r>oo:dfsa:13243
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin

 

#这样操做起来特别麻烦，如何简单操做呢，咱们能够用到egrep命令了，或者grep -E

[root@centos6 ~]# egrep 'o{2}' passwd 
root:x:0:0:root:/root:/bin/bash
ahkdhfa:r>oo:dfsa:13243
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
[root@centos6 ~]# grep -E 'o{2}' passwd 
root:x:0:0:root:/root:/bin/bash
ahkdhfa:r>oo:dfsa:13243
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
[root@centos6 ~]# egrep 'o+t' passwd 
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin
[root@centos6 ~]# egrep 'o?t' passwd 
root:x:0:0:root:/root:/bin/bash
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
operator:x:11:0:operator:/root:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
vcsa:x:69:69:virtual console memory owner:/dev:/sbin/nologin
saslauth:x:499:76:Saslauthd user:/var/empty/saslauth:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
ntp:x:38:38::/etc/ntp:/sbin/nologin
[root@centos6 ~]# egrep 'o?1o' passwd 
bin:x:1o:1:bin:/bin:/sbin/nologin
[root@centos6 ~]# grep -E 'root|nologin' passwd 
root:x:0:0:root:/root:/bin/bash
bin:x:1o:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
gopher:x:13:30:gopher:/var/gopher:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
vcsa:x:69:69:virtual console memory owner:/dev:/sbin/nologin
saslauth:x:499:76:Saslauthd user:/var/empty/saslauth:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
ntp:x:38:38::/etc/ntp:/sbin/nologin