2018-03-12 Amin Linux Learning

9.1 Regular Introduction grep (UP)

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    各种编程语言中都有正则，原理是一样的    本章主要学习 grep/egrep、sed、awk掌握规律grep     grep [-cinvABC] ‘work‘ filename        -c  行数        -i  不区分大小写        -n  显示行号        -v  取反        -r  遍及所有子目录        -A  后面跟数字，过滤出符合要求的行以及下面n行        -B  后面跟数字，过滤出符合要求的行以及上面n行        -C  后面跟数字，同时过滤出符合要求的行以及上下各n行    [[email protected] grep]# grep -c ‘nologin‘ passwd    16    [[email protected] grep]# grep -n ‘nologin‘ passwd    [[email protected] grep]# grep -i -c ‘nologin‘ passwd    16    [[email protected] grep]# grep -v -c ‘nologin‘ passwd    4    [[email protected] grep]# grep -vc ‘nologin‘ passwd    4    [[email protected] grep]# grep -v ‘nologin‘ passwd    root:x:0:0:root:/root:/bin/bash    sync:x:5:0:sync:/sbin:/bin/sync    shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown    halt:x:7:0:halt:/sbin:/sbin/halt    [[email protected] grep]# grep -A2 ‘root‘ passwd

9.2 grep (middle)

grep/egrep example grep-n ' root '/etc/passwd grep-nv ' nologin '/etc/passwd grep ' [0-9] '/etc/ininttab grep-v ' [0  -9] '/etc/inittab grep-v ' ^# ' inittab grep-v ' ^# ' inittab|grep-v ' ^$ ' grep ' ^[^a-za-z] ' test.txt grep ' r.o ' Test.txt grep ' oo ' test.txt grep '. * ' test.txt grep ' o\{2\} '/etc/passwd egrep ' o{2} '/etc/passwd egrep ' O + '/etc/passwd egrep ' oo? '/etc/passwd egrep ' root|nologin '/etc/passwd egrep ' (oo) {2} '/etc/passwd [Emai        L protected] grep]# grep-n ' ^# ' Inittab 1:# Inittab is the no longer used when using SYSTEMD.        2:# 3:# ADDING CONFIGURATION Here is the NO EFFECT on YOUR SYSTEM. 4:# 5:# Ctrl-alt-delete is handled by/usr/lib/systemd/system/ctrl-alt-del.target 6:# 7:# systemd use S ' targets ' instead of runlevels. By default, there is both main targets:8:# 9:# multi-user.target:analogous to runlevel 3 10:# graph   Ical.target:analogous to RunLevel 5     11:# 12:# to view current default target, run:16:# systemctl get-default 17:# 18:# to SE  t a default target, run:19:# systemctl set-default target.target 20:# [[email protected] grep]# Grep-nv ' ^# ' inittab 13:adfafsafd 14:ssss 15:66666 [[email protected] grep]# grep-n '        [^0-9] ' Inittab 1:# inittab is no longer used when using SYSTEMD.        2:# 3:# ADDING CONFIGURATION Here is the NO EFFECT on YOUR SYSTEM. 4:# 5:# Ctrl-alt-delete is handled by/usr/lib/systemd/system/ctrl-alt-del.target 6:# 7:# systemd use S ' targets ' instead of runlevels. By default, there is maintargets:8:# 9:# multi-user.target:analogous to runlevel 3 10:# Graphi        Cal.target:analogous to RunLevel 5 11:# 12:# to view current default target, RUN:13:ADFAFSAFD 14:ssss 16:# systemctl get-default 17:# 18:# To Set a default target, run:19:# systemctl set-default target.target 20:# [[email protected] Gr        ep]# grep-n ' ^[^0-9] ' inittab 1:# inittab are no longer used when using SYSTEMD.        2:# 3:# ADDING CONFIGURATION Here is the NO EFFECT on YOUR SYSTEM. 4:# 5:# Ctrl-alt-delete is handled by/usr/lib/systemd/system/ctrl-alt-del.target 6:# 7:# systemd use S ' targets ' instead of runlevels. By default, there is both main targets:8:# 9:# multi-user.target:analogous to runlevel 3 10:# graph        Ical.target:analogous to RunLevel 5 11:# 12:# to view current default target, RUN:13:ADFAFSAFD 14:ssss 16:# systemctl get-default 17:# 18:# to set a default target, run:19:# systemctl s Et-default target.target 20:# [[email protected] grep]# grep-nv ' ^[^0-9] ' inittab 15:66,666

9.3 grep (bottom)

 . Match. Any one of the characters in each of the two words * repeat * the character on the left 0 or countless + repeat + left 1 to countless? Repeat?  0 or 1 times of the preceding character | or () Find out the identification of the group string () + multiple repeating group strings [[email protected] grep]# grep ' r.o ' passwd root:x:0:0:root:/root:/bin/bash o Perator:x:11:0:operator:/root:/sbin/nologin [[email protected] grep]# grep ' {2} ' passwd [[email protected    ] grep]# grep ' o{2} ' passwd [[email protected] grep]# grep ' 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/spool/postfix:/sbin/nologin Bacula:x:133:133:bacula Backup System:/var/ Spool/bacula:/sbin/nologin grep-e ' o{2} ' passwd = = Egrep ' o{2} ' passwd [[email protected] grep]# egrep ' o+ O ' passwd [[email protected] grep]# grep-e ' root|nologin ' passwd [[email protected] data]# grep-r--INCL Ude= "*.php" ' eval '/tmp/data/tmp/data/ext.php:eval  

2018-03-12 Amin Linux Learning