Linux starter grep Regular expression case

grep Regular Expression case

Case one:

1. Display the line in the/proc/meminfo file that begins with the size S; (Requires: use two ways)

#grep-i ' ^s '/proc/meminfo#grep ' ^[ss] '/proc/meminfo#grep-e ' ^ (s| S) '/proc/meinfo

2. Display lines in the/etc/passwd file that do not end in/bin/bash

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

3. Show user RPC default shell program

#grep ' ^\<rpc\> '/etc/passwd | Cut-d:-f7

4. Find out the two-bit or three-digit number in/etc/passwd

#grep ' \<[0-9][0-9]\?\> '/etc/passwd#grep ' \<[0-9]\{2,3\}\> '/etc/passwd

5. Display a line in a/etc/grub2.cfg file that starts with at least one whitespace character and that is followed by a non-whitespace character

#grep ' ^[[:space:]]\+.*[^[:space:]] '/etc/grub2.cfg

6. Find the line ending with ' LISTEN ' followed by any whitespace character in the result of the "Netstat-tan" command

#netstat-tan '. *listen[[:space:]]*$ '

7. Add user bash, Testbash, basher, and Nologin (whose shell is/sbin/nologin), then find the line in the/etc/passwd file with the name of the shell

#grep ' ^\<\ (. *\) \>.*/\1$ '/etc/passwd#grep ' ^\<\ (. *\) \>.*\<\1\>$ '/etc/passwd

Case TWO:

1. Displays the UID and default shell of the current system root, mage, or Wang user

#grep-E ' ^ (root|mage|wang) \> '/etc/passwd |cut-d:-f7

2. Find the line at the beginning of the/etc/rc.d/init.d/functions file that has a word (including an underscore) followed by a parenthesis

#grep-e-o ' ^\<[[:alnum:]_]+\>\ (\) '/etc/rc.d/init.d/functins

3. Use Egrep to remove its base name in/etc/rc.d/init.d/functions

#echo "/etc/rc.d/init.d/functions" | GREP-E-O ' [^/]+/?$ '

4. Use Egrep to remove the directory name of the path above

#echo "/etc/rc.d/init.d/functions" | Grep-e ' (/.*/) '

5. Count the number of logons per remote host IP address logged in as root

#last | Grep-o ' root\>.*\ ([[:d igit:]]\{1,3\}\.\) \{3\}[[:d igit:]]\> ' | Tr-s ' | Cut-d '-f3 | Uniq-c

6. Use extended regular expressions to represent 0-9, 10-99, 100-199, 200-249, 250-255, respectively

#grep-E ' \< ([0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5]) \> '

7. Display all IPV4 addresses in ifconfig command results

#ifconfig | Grep-o ' \ (\ ([0-9]\|1[0-9]\|1[0-9]{2}\|2[0-4][0-9]\|25[0-5]\) \.\) \{3\}\ ([0-9]\|1[0-9]\|1[0-9]{2}\|2[0-4][0-9]\| 25[0-5]\) '

Case THREE:

4, take the local IP address

#ifconfig | grep ' inet addr ' | GREP-E-O ' ([[1-9]|1[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-4]) \.) {3} ([1-9]|1[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-4]) '

5, the use of the number of partition utilization

DF | Grep-o ' \<[0-9]\+% '

6. Count the number of occurrences of each word in the/etc/init.d/functions file and display it from high to low by frequency

Non-Regular:

#cat/etc/init.d/functions | Tr-cs ' [: Alpha:] ' |  Tr ' \ n ' | Sort | uniq-c | Tr-s ' | Sort-t "-K 1NR

Regular plus substitution:

#cat/etc/init.d/functions | Tr ' _ ' | Grep-o ' \<[a-za-z]\+\> ' | Sort | uniq-c | Tr-s ' | Sort-t "-k2 NR

Pure is:

#cat/etc/init.d/functions | Grep-o--color ' \<\ ([a-za-z_]\) \+\> ' | grep--color ' \<[#a-za-z]\+\> ' | Sort | uniq-c | Grep-o "[0-9]\+[[:space:]][a-za-z]\+" | Sort-t '-k1-nr

7,/etc/rc.d/init.d/functions or/etc/rc.d/init.d/functions/"Fetch directory Name

#DIR = "/etc/rc.d/init.d/functions" #DIR1 = "/etc/rc.d/init.d/functions/" #echo ${dir} | grep ' \ (/.*/\) ' #echo ${dir1} | Tr '/' | Cut-d '-f1-$[' echo $DIR | tr '/' ' | wc-w ' | TR '/' Echo ${dir} | Grep-o '/.*[^/] ' | grep--color-o '/.*/'

The extension uses the SED command:

echo "/sdsdf/sgdsg/sdgg/fgdfhdfh/" | Sed ' s/[^\/]\+\/\?$//g '

This article is from the "Excalibur Trunks-kun" blog, please be sure to keep this source http://mengzhaofu.blog.51cto.com/10085198/1836489

Linux starter grep Regular expression case