grep and Regular Expressions 02-related exercises

(1), display lines in the/proc/meminfo file that begin with size S

# grep-i ' ^s '/proc/meminfo

(2), display lines in the/etc/passwd file that do not end in/bin/bash

#grep-V ' \/bin\/bash$ '/etc/passwd

(3), display the user name of the user with the largest ID number in the/etc/passwd file and its shell

Method 1:# cat/etc/passwd|cut-d:-f3|sort-n|tail-1|xargs getent passwd|cut-d:-f1,7nfsnobody:/sbin/nologin Method 2: # Sort-t: -k3-n/etc/passwd|tail-1|cut-d:-f1,7nfsnobody:/sbin/nologin

(4), display the user RPC default shell program

Method 1:# grep-w ' ^rpc '/etc/passwd |awk-f: ' {print $7} ' method 2:# grep ' \<rpc\> '/etc/passwd |cut-d:-f7

(5), find out the number of two or three digits in the/etc/passwd

# grep-o ' [0-9]\{2,3\}* '/etc/passwd

(6), a line that displays at least one whitespace character in a/etc/grub2.cfg file, followed by a non-whitespace character

# egrep ' ^[[:space:]]+[^[:space:]] '/etc/grub2.cfg

(7), find the result of the "Netstat-tan" command with ' LISTEN ' followed by 0, 1 or more whitespace characters end of the line

# netstat-tan|grep "listen[[:space:]]*$"

(8), remove the remote connection to the native IP address, and sort.

 method 1:[[email protected] ~]# netstat -tnp|awk -f   "[ :]+"   ' nr>2{print $6} ' |uniq -c|sort -r 2 172.16.251.121 1  172.16.250.14 Method 2:[[email protected] ~]# netstat -tnp|tail -n +3|awk - f  "[ :]+"   ' {print $6} ' |uniq -c|sort -r 2 172.16.251.121 1  172.16.250.14  experience here tail -n +3  This means that the last line (including line 3rd) is printed starting from line 3rd 

Method 3:[[email protected] ~]# netstat-tnp|tail-n +3|cut-d:-f2|tr-s "" |cut-d ""-f2|uniq-c|sort-r 2 172.16.251.121 1 172.16.250.14 experience here the tr-s means that the delimiter between the adjacent two fields is compressed to 1 for example: [[email protected] ~]# cat test.txt 1:::::::::::2:::3 [[EMA Il protected] ~]# tr-s ":" <test.txt 1:2:3

(9), find the user name and shell name consistent line in the/etc/passwd file

Method 1: [[email protected] ~]# egrep "^ (. *):. *\1$"/etc/passwdsync:x:5:0:sync:/sbin:/bin/syncshutdown:x:6:0:shutdown:/ Sbin:/sbin/shutdownhalt:x:7:0:halt:/sbin:/sbin/haltnologin:x:1004:1004::/home/nologin:/sbin/nologin Method 2:[[email Protected] ~]# egrep ' (\<[[:alpha:]]*\>). *\1$ '/etc/passwdsync:x:5:0:sync:/sbin:/bin/syncshutdown:x:6:0: Shutdown:/sbin:/sbin/shutdownhalt:x:7:0:halt:/sbin:/sbin/haltnologin:x:1004:1004::/home/nologin:/sbin/nologin

(10), displays the UID of the current system root, mage, or Wang user and Default Shell

# egrep "^root\>|^mage\>|^wang\>"/etc/passwd|cut-d:-f3,7

(11), find a word in the/etc/rc.d/init.d/functions file ( including underscores) followed by a parenthesis line

# egrep ' [[: Alpha:]0-9_]+\ (\) '/etc/rc.d/init.d/functions

(12), use Egrep to remove its base name in/etc/rc.d/init.d/functions

[[email protected] ~]# echo "/etc/rc.d/init.d/functions" |egrep-o ' [[: Alpha:].] +/?$ ' Functions[[email protected] ~]# echo "/etc/rc.d/init.d/" |egrep-o ' [[: Alpha:].] +/?$ ' init.d/have a good experience? The simplest method: BaseName, Dirname[[email protected] ~]# basename/etc/rc.d/init.d/functionsfunctions[[ Email protected] ~]# DIRNAME/ETC/RC.D/INIT.D/FUNCTIONS/ETC/RC.D/INIT.D

(13), use Egrep to remove the directory name of the above path

# echo "/etc/rc.d/init.d/functions" |egrep-o "^.*/"

(14), find the IPV4 address of the ifconfig command result in the machine

[[email protected] ~]# ifconfig eno16777736|head-2|tail-1|cut-d ""-f10 172.16.251.126[[email protected] ~]# ifconfig Eno16777736|awk-f "" ' Nr==2{print $ {} ' 172.16.251.126[[email protected] ~]# ifconfig eno16777736|awk-f "[]+" ' Nr==2{pri NT $172.16.251.12} '

(15), Detect/TMP permissions to display in digital form

Using the Stat command

Method 1:[[email protected] ~]# stat/tmp |head-4|tail-1|egrep-o "[0-9]{4}" 1777 method 2:[[email protected] ~]# stat/tmp |head- 4|tail-1 Access: (1777/DRWXRWXRWT) Uid: (0/root) Gid: (0/root) [[email protected] ~]# stat/tmp |head- 4|tail-1|cut-d/-f1|cut-d "("-f2 1777

Not to be continued ...

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grep and Regular Expressions 02-related exercises