·正則就是一串有規律的字符串

·掌握好正則對於編寫shell腳本有很大幫助

·各種編程語言中都有正則，原理是一樣的

·本章將要學習grep/egrep、sed、awk

grep [-cinvABC] 'word' filename

-c 行數

-i 不區分大小寫

-n 顯示行號

-v 取反

-r 遍歷所有子目錄

-A 後面跟數字，過濾出符合要求的行以及下面n行

-B 同上，過濾出符合要求的行以及上面n行

-C 同上，同時過濾出符合要求的行以及上下各n行

[root@localhost ~]# mkdir grep
[root@localhost ~]# cd grep/
[root@localhost grep]# cp /etc/passwd .
[root@localhost grep]# ls
passwd
[root@localhost grep]# grep 'nologin' passwd
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
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
polkitd:x:999:997:User for polkitd:/:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
chrony:x:998:996::/var/lib/chrony:/sbin/nologin
[root@localhost grep]# grep -c 'nologin' passwd        ##-c 顯示行數
15
[root@localhost grep]# grep -n 'nologin' passwd        ##-n 顯示行號
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:operator:x:11:0:operator:/root:/sbin/nologin
11:games:x:12:100:games:/usr/games:/sbin/nologin
12:ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
13:nobody:x:99:99:Nobody:/:/sbin/nologin
14:systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
15:dbus:x:81:81:System message bus:/:/sbin/nologin
16:polkitd:x:999:997:User for polkitd:/:/sbin/nologin
17:postfix:x:89:89::/var/spool/postfix:/sbin/nologin
18:sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
19:chrony:x:998:996::/var/lib/chrony:/sbin/nologin
[root@localhost grep]# vim passwd                     ##vim中把第二行nologin改為NOLogin
[root@localhost grep]# grep -n 'nologin' passwd         ##大寫NOLogin就無法識別
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:operator:x:11:0:operator:/root:/sbin/nologin
11:games:x:12:100:games:/usr/games:/sbin/nologin
12:ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
13:nobody:x:99:99:Nobody:/:/sbin/nologin
14:systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
15:dbus:x:81:81:System message bus:/:/sbin/nologin
16:polkitd:x:999:997:User for polkitd:/:/sbin/nologin
17:postfix:x:89:89::/var/spool/postfix:/sbin/nologin
18:sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
19:chrony:x:998:996::/var/lib/chrony:/sbin/nologin
[root@localhost grep]# grep -in 'nologin' passwd         ##-i 不區分大小寫，可識別第二行NOLogin
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:operator:x:11:0:operator:/root:/sbin/nologin
11:games:x:12:100:games:/usr/games:/sbin/nologin
12:ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
13:nobody:x:99:99:Nobody:/:/sbin/nologin
14:systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
15:dbus:x:81:81:System message bus:/:/sbin/nologin
16:polkitd:x:999:997:User for polkitd:/:/sbin/nologin
17:postfix:x:89:89::/var/spool/postfix:/sbin/nologin
18:sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
19:chrony:x:998:996::/var/lib/chrony:/sbin/nologin
[root@localhost grep]# grep -inv 'nologin' passwd         ##-v 取反，把不含nologin的行過濾出來
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@localhost grep]# grep -r 'Streaming' /etc/##-r 遍歷/etc/目錄下，包含Streaming的行
/etc/services:nmsp            537/tcp                 # Networked Media Streaming Protocol
/etc/services:nmsp            537/udp                 # Networked Media Streaming Protocol
/etc/services:h263-video      2979/tcp                # H.263 Video Streaming
/etc/services:h263-video      2979/udp                # H.263 Video Streaming
/etc/services:daqstream       7411/tcp                # Streaming of measurement
/etc/services:daqstream       7411/udp                # Streaming of measurement
/etc/services:hp-pdl-datastr  9100/udp        pdl-datastream  # PDL Data Streaming Port
/etc/services:bmdss           13823/tcp               # Blackmagic Design Streaming Server
匹配到二進制文件 /etc/udev/hwdb.bin
[root@localhost grep]# grep -r 'root' /etc/ > grep.txt | grep 'passwd' grep.txt
/etc/passwd:root:x:0:0:root:/root:/bin/bash
/etc/passwd:operator:x:11:0:operator:/root:/sbin/nologin
/etc/passwd-:root:x:0:0:root:/root:/bin/bash
/etc/passwd-:operator:x:11:0:operator:/root:/sbin/nologin
/etc/postfix/main.cf:# the system passwd file in the chroot jail is just not practical.
[root@localhost grep]# grep -nA2 'root' passwd                    ##-A2 列出符合要求的行以及下面2行
1:root:x:0:0:root:/root:/bin/bash
2-bin:x:1:1:bin:/bin:/sbin/NOLogin
3-daemon:x:2:2:daemon:/sbin:/sbin/nologin
--
10:operator:x:11:0:operator:/root:/sbin/nologin
11-games:x:12:100:games:/usr/games:/sbin/nologin
12-ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
[root@localhost grep]# grep -nB2 'root' passwd                    ##-B2 列出符合要求的行以及上面2行
1:root:x:0:0:root:/root:/bin/bash
--
8-halt:x:7:0:halt:/sbin:/sbin/halt
9-mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
10:operator:x:11:0:operator:/root:/sbin/nologin
[root@localhost grep]# grep -nC2 'root' passwd                    ##-C2 列出符合要求的行以及上下2行
1:root:x:0:0:root:/root:/bin/bash
2-bin:x:1:1:bin:/bin:/sbin/NOLogin
3-daemon:x:2:2:daemon:/sbin:/sbin/nologin
--
8-halt:x:7:0:halt:/sbin:/sbin/halt
9-mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
10:operator:x:11:0:operator:/root:/sbin/nologin
11-games:x:12:100:games:/usr/games:/sbin/nologin
12-ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin

9.2 grep(中)

grep/egrep 示例

[root@localhost grep]# grep -n 'root' /etc/passwd##顯示行號
1:root:x:0:0:root:/root:/bin/bash
10:operator:x:11:0:operator:/root:/sbin/nologin
[root@localhost grep]# grep -nv 'root' /etc/passwd##顯示行號，並且取反
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
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
9:mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
11:games:x:12:100:games:/usr/games:/sbin/nologin
12:ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
13:nobody:x:99:99:Nobody:/:/sbin/nologin
14:systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
15:dbus:x:81:81:System message bus:/:/sbin/nologin
16:polkitd:x:999:997:User for polkitd:/:/sbin/nologin
17:postfix:x:89:89::/var/spool/postfix:/sbin/nologin
18:sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
19:chrony:x:998:996::/var/lib/chrony:/sbin/nologin
[root@localhost grep]# grep '[0-9]' /etc/inittab ##含有數字的行
# multi-user.target: analogous to runlevel 3
# graphical.target: analogous to runlevel 5
[root@localhost grep]# grep -v '[0-9]' /etc/inittab ##不含有數字的行
# inittab is no longer used when using systemd.
#
# ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
#
# Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target
#
# systemd uses 'targets' instead of runlevels. By default, there are two main targets:
#
#
# To view current default target, run:
# systemctl get-default
#
# To set a default target, run:
# systemctl set-default TARGET.target
#
[root@localhost grep]# grep -n '^#' /etc/inittab ##以#開頭的行
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:#
[root@localhost grep]# vim inittab ##加入一段胡亂的文字

[root@localhost grep]# grep -v '^#' inittab ##不以#開頭的行
&&*&*[]%%
999999999
aaaaaa
jiojapjaoijfpaoijsdfpoali
77777a7777
[root@localhost grep]# grep -v '^#' inittab | grep -v '^&'##不以#開頭的行中，同時不以&開頭的行
999999999
aaaaaa
jiojapjaoijfpaoijsdfpoali
77777a7777
[root@localhost grep]# grep '[^0-9]' inittab ##[^0-9]只要有不包含數字的行
# inittab is no longer used when using systemd.
#
# ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
#
# Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target
&&*&*[]%%
#
# systemd uses 'targets' instead of runlevels. By default, there are two main targets:
#
# multi-user.target: analogous to runlevel 3
# graphical.target: analogous to runlevel 5
#
aaaaaa
# To view current default target, run:
# systemctl get-default
jiojapjaoijfpaoijsdfpoali
#
# To set a default target, run:
# systemctl set-default TARGET.target
77777a7777
#
[root@localhost grep]# grep '^[^0-9]' inittab ##以非數字開頭的行
# inittab is no longer used when using systemd.
#
# ADDING CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
#
# Ctrl-Alt-Delete is handled by /usr/lib/systemd/system/ctrl-alt-del.target
&&*&*[]%%
#
# systemd uses 'targets' instead of runlevels. By default, there are two main targets:
#
# multi-user.target: analogous to runlevel 3
# graphical.target: analogous to runlevel 5
#
aaaaaa
# To view current default target, run:
# systemctl get-default
jiojapjaoijfpaoijsdfpoali
#
# To set a default target, run:
# systemctl set-default TARGET.target
#
[root@localhost grep]# grep -v '^[^0-9]' inittab ##以數字開頭的行
999999999
77777a7777

9.3 grep(下)

. 一個任意字符

* *前面的字符重復0個或多次（*要和前面的字符組合起來用）

.* 通配，無論有沒有字符都匹配

{} 表示{}前面的字符重復次數範圍 ，{2}前面字符重復2次

+ +前面的字符重復1次或多次

？ ？前面的字符重復0次或1次

| |表示或者

[root@localhost grep]# grep 'r.o' passwd ## . 匹配任何單個字符
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin
chrony:x:998:996::/var/lib/chroooony:/sbin/nologin
[root@localhost grep]# grep 'o*o' passwd ## **左邊的字符重復0-n次
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
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
polkitd:x:999:997:User for polkitd:/:/sbin/nologin
postfix:x:89:89::/var/spooooool/postfix:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
chrony:x:998:996::/var/lib/chroooony:/sbin/nologin
[root@localhost grep]# grep '.*' passwd         ##任意一個單字符重復0-n次，就是任意字符
root:x:0:0:root:/root:/bin/bash                ##.* 就是通配
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
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
polkitd:x:999:997:User for polkitd:/:/sbin/nologin
postfix:x:89:89::/var/spooooool/postfix:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
chrony:x:998:996::/var/lib/chroooony:/sbin/nologin
[root@localhost grep]# grep 'o\{2\}' passwd             ##兩個o
root:x:0:0:root:/root:/bin/bash
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
postfix:x:89:89::/var/spooooool/postfix:/sbin/nologin
chrony:x:998:996::/var/lib/chroooony:/sbin/nologin
[root@localhost grep]# grep 'o\{0,3\}' passwd             ##o重復0-3次
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
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
polkitd:x:999:997:User for polkitd:/:/sbin/nologin
postfix:x:89:89::/var/spooooool/postfix:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
chrony:x:998:996::/var/lib/chroooony:/sbin/nologin

·egrep = grep -E

如果不想用脫義符，那麽用egrep或grep -E

[root@localhost grep]# egrep 'o{2}' passwd
root:x:0:0:root:/root:/bin/bash
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
postfix:x:89:89::/var/spooooool/postfix:/sbin/nologin
chrony:x:998:996::/var/lib/chroooony:/sbin/nologin
[root@localhost grep]# grep -E 'o{2}' passwd
root:x:0:0:root:/root:/bin/bash
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
postfix:x:89:89::/var/spooooool/postfix:/sbin/nologin
chrony:x:998:996::/var/lib/chroooony:/sbin/nologin
[root@localhost grep]# egrep '(oo){2}' passwd             ## oo字符重復兩次
postfix:x:89:89::/var/spooooool/postfix:/sbin/nologin
chrony:x:998:996::/var/lib/chroooony:/sbin/nologin
[root@localhost grep]# egrep 'o+t' passwd                 ## +前面的o出現一次或多次
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin
[root@localhost grep]# egrep 'o?t' passwd                 ## ？前面的o出現0或1次
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
systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
polkitd:x:999:997:User for polkitd:/:/sbin/nologin
postfix:x:89:89::/var/spooooool/postfix:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
[root@localhost grep]# egrep 'root|nologin' passwd         ## | 表示或者，| 前後只要出現一個
root:x:0:0:root:/root:/bin/bash
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
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
polkitd:x:999:997:User for polkitd:/:/sbin/nologin
postfix:x:89:89::/var/spooooool/postfix:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
chrony:x:998:996::/var/lib/chroooony:/sbin/nologin

2018-1-15 6周1次課 grep