Use of grep in Linux CentOS 7

9.1 Regular Introduction _grep (1) What is a regular

Regular is a string of regular strings. Mastering a good regular is a great help for the shell. Every language has a regular, the principle is the same. The main commands are: Grep/egrep sed awk.

(2) grep

grep  filters The specified keyword grep [-cinvrabc]  ' word '  filenamegrep -c  displays the total number of lines that contain keywords Grep -n   Show line numbers that contain keywords grep -i  case-insensitive grep -v  grep -r  traverse all subdirectories grep -a  back root number , filter out the line that meets the requirements and the following n rows grep -b  the root number, filter out the rows that meet the requirements, and the number of n rows above grep -c , filter out the rows that meet the requirements, and the next n rows 

[[email protected] ~]# grep -c root /etc/passwd2[[email protected] ~]# [[email protected] ~]# grep -n root /etc/passwd1:root:x:0:0:root:/root:/bin/ Bash10:operator:x:11:0:operator:/root:/sbin/nologin[[email protected] ~]#[[email protected]  ~]# grep -vn root /etc/passwd2:bin:x:1:1:bin:/bin:/sbin/nologin3:daemon:x:2:2:daemon :/sbin:/sbin/nologin4:adm:x:3:4:adm:/var/adm:/sbin/nologin5:lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin6:sync:x : 5:0:sync:/sbin:/bin/sync7:shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown8:halt:x:7:0:halt:/sbin:/sbin/halt9: MAIL:X:8:12:MAIL:/VAR/SPOOL/MAIL:/SBIN/NOLOGIN11:GAMES:X:12:100:GAMES:/USR/GAMES:/SBIN/NOLOGIN12:FTP:X:14:50: ftp user:/var/ftp:/sbin/nologin13:nobody:x:99:99:nobody:/:/sbin/nologin[[email protected] tmp]#  grep -i root 1.txt 1root:x:0:0:root:/root:/bin/bash1root:x:0:0:root:/root:/bin/ Bashoperator:x:11:0:operator:/root:/sbin/nologin[[email protected] tmp]#[[email protected] ~]# grep -r  root /tmp//tmp/history_bak.log:      1 ./root/shell/mail.sh 111  111/tmp/history_bak.log:      1 /bin/grep root /etc/passwd/ Tmp/history_bak.log:      2 /usr/local/mysql/bin/mysql -u root  -p/tmp/history_bak.log:      1 /usr/local/mysql/bin/mysqldump -u  root -p /tmp/history_bak.log:      1 /usr/local/mysql/bin/ mysqldump -u root -p password  "qing123." /tmp/history_bak.log:      1 awk  "/root/"  1.txt/tmp/history_ bak.log:      1 awk  "/root|fxq/"  1.txt/tmp/history_bak.log:       1 awk /root|fxq/ 1.txt/tmp/history_bak.log:      1 cat /etc/passwd | grep  Root/tmp/2.txt:1root:x:0:0:root:/root:/bin/bash/tmp/2.txt:operator:x:11:0:operator:/root:/sbin/nologin/tmp/1. txt:1root:x:0:0:root:/root:/bin/bash/tmp/1.txt:operator:x:11:0:operator:/root:/sbin/nologin[[email  Protected] ~]# grep -na2 root /etc/passwd1:root:x:0:0:root:/root:/bin/bash2-bin:x:1:1 : bin:/bin:/sbin/nologin3-daemon:x:2:2:daemon:/sbin:/sbin/nologin--10:operator:x:11:0:operator:/root:/sbin/ nologin11-games:x:12:100:games:/usr/games:/sbin/nologin12-ftp:x:14:50:ftp user:/var/ftp:/sbin/nologin[[ Email protected] ~]# [[email protected] tmp]# grep -nb2 root /etc /passwd1:root:x:0:0:root:/root:/bin/bash--8-halt:x:7:0:halt:/sbin:/sbin/halt9-mail:x:8:12:mail:/var/spool/mail :/sbin/nologin10:operator:x:11:0:operator:/root:/sbin/nologin[[email protected] tmp]# [[email  protected] tmp]# grep -nc2 root /etc/passwd1:root:x:0:0:root:/root:/bin/bash2-bin:x:1:1:bin:/bin:/sbin/ nologin3-daemon:x:2:2:daemon:/sbin:/sbin/nologin--8-halt:x:7:0:halt:/sbin:/sbin/halt9-mail:x:8:12:mail:/var/ spool/mail:/sbin/nologin10:operator:x:11:0:operator:/root:/sbin/nologin11-games:x:12:100:games:/usr/games:/ sbin/nologin12-ftp:x:14:50:ftp user:/var/ftp:/sbin/nologin[[email protected] tmp]#

9.2 grep in

Grep-n ' root '/etc/passwdgrep-nv ' root '/etc/passwdgrep ' [0-9] '/etc/inittab filter lines with numbers grep-v ' [0-9] '/etc/inittab filter not Contains digitized lines grep-v ' ^# '/etc/inittab filter with non-# start line grep ' ^[^a-za-z] ' test.txt filter lines starting with non-letters

[[email protected] tmp]# grep  ' [0-9] '  /etc/passwdroot:x:0:0:root:/root:/bin/bashbin:x : 1:1:bin:/bin:/sbin/nologindaemon:x:2:2:daemon:/sbin:/sbin/nologinadm:x:3:4:adm:/var/adm:/sbin/nologinlp:x:4:7 : lp:/var/spool/lpd:/sbin/nologinsync:x:5:0:sync:/sbin:/bin/syncshutdown:x:6:0:shutdown:/sbin:/sbin/ shutdownhalt:x:7:0:halt:/sbin:/sbin/halt[[email protected] tmp]# grep -vn  ' [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.target6: #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:# [[ email protected] tmp]#  [[email protected] tmp]# grep -nv  ' ^# '  1.txt 4:33335:11116:1root:x:0:0:root:/root:/bin/bash 7:1root:x:0:0:root:/root:/bin/bash 8 : Bin:x:1:1:bin:/bin:/sbin/nologin

9.3 grep under

grep ' R.O ' test.txt. Match any character grep ' oo* ' test.txt * match * preceding character any time (>=0) grep '. * ' test.txt. * Match any arbitrary character grep ' o\{2\} '/etc /PASSWD grep-e ' o{2} '/etc/passwdegrep ' o{2} '/etc/passwdegrep ' o+ '/etc/passwd + match + 1 or more times preceding (>=1) egrep ' oo? '/etc/p Asswd? match? Front character 0 or 1 times (0 or 1) egrep ' Root|nologin '/etc/passwd match root or Nologinegrep ' (oo) {2} '/etc/passwd range

[[email protected] tmp]# egrep ' o{2} '/etc/passwdroot:x:0:0:root:/root:/bin/bashlp:x:4:7:lp:/var/spool/lpd:/sbin/ Nologinmail:x:8:12:mail:/var/spool/mail:/sbin/nologinoperator:x:11:0:operator:/root:/sbin/nologinpostfix:x : 89:89::/var/spool/postfix:/sbin/nologinmailnull:x:47:47::/var/spool/mqueue:/sbin/nologinsmmsp:x:51:51::/var/ Spool/mqueue:/sbin/nologin[[email protected] tmp]#

Extended

Filter all the lines in the *.php document that contain eval in a directory

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

[[email protected] fxq]# grep -r --include= ' *.php '   ' eval '  /  / Backup/hszd_zabbix/bak/var_www_html_zabbix/jsloader.php:header (' cache-control: public,  Must-revalidate ');/backup/hszd_zabbix/bak/var_www_html_zabbix/include/triggers.inc.php: * substitute  macros in the expression with the given values and evaluate  its result./backup/hszd_zabbix/bak/var_www_html_zabbix/include/triggers.inc.php:function  Evalexpressiondata ($expression,  $replaceFunctionMacros)  {/backup/hszd_zabbix/bak/var_www_html_zabbix /include/triggers.inc.php:eval (' $result  =  trim ($evStr). '); backup/hszd_zabbix/bak/var_www_html_zabbix/include/schema.inc.php: ' Evaltype '  => array (/backup/ hszd_zabbix/bak/var_www_html_zabbix/include/schema.inc.php: ' Evaltype '  => array (/backup/hszd_ zabbix/bak/var_www_html_zabbix/include/schema.inc.php: ' Evaltype '  =>  array ( 

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Use of grep in Linux CentOS 7