What commands does linux use to process text?

1 、 grep

2. Regular expression

3. Extend regular expressions

4 、 vim

# #

Cat-A

Cat-ns

Cat-b

Tac

Less: pgup; pgdown

? N/N

/

Openssl rand-base64 100 | tr-dc "[: alnum:]" | head-c12

[root@centos6 / app] # openssl rand-base64 100 | tr-dc "[: alnum:]" | head-c124oa9aPP1tr9I

Tail-f is similar: tailf

Tail-F trace file name

Date-d "- 1day"

[root@centos6 / app] # cut-d:-f 1pr 3 / etc/passwd

Df | grep ^ / dev/sd | sed-r "sswap. * [] + ([0-9] {1pm 3})%. * /\ 1 /" df-I | grep ^ / dev/sd | sed-r "sramp. * [] + ([0-9] {1 Magazine 3})%. * /\ 1 /" [root@node4~] # ifconfig eth0 | head-N2 | tail-N1 | tr-s "| cut-d"-f3192.168.137.47 [root@centos6 ~] # ifconfig Eth0 | head-N2 | tail-N1 | cut-d ":"-f2 | cut-d ""-f1192.168.137.6

[root@node4/app] # cut-d:-F1 etc/passwd 3 / etc/passwd | sort-t:-K2-n

Root:0

Bin:1

Daemon:2

Adm:3

Lp:4

Uniq-c

[root@node4/app] # cat / var/log/httpd/access_log | cut-d ""-F1 | sort | uniq-c | sort-nr

7 192.168.137.1

2 192.168.0.118

Diff

Patch

[root@node4/app] # cat F1 whereis [root@node4/app] # cat f2whosi [root@node4/app] # diff-u f1 f2 > diff.log [root@node4/app] # rm-f F1 [root@node4/app] # patch-b f2 diff.log patching file f2Reversed (or previously applied) patch detected! Assume-R? [n] y [root@node4/app] # mv f2 f1 [root@node4/app] # mv f2.orig f2 [root@node4/app] # cat f1 f2whereiswhosi

Linux text processing three Musketeers:

Grep:

Man grep

Grep-nA3 root / etc/passwd

Grep-c

[root@node4/app] # grep-nA3 root / etc/passwd

1:root:x:0:0:root:/root:/bin/bash2-bin:x:1:1:bin:/bin:/sbin/nologin3-daemon:x:2:2:daemon:/sbin:/sbin/nologin4-adm:x:3:4:adm:/var/adm:/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/nologin13-nobody:x:99:99:Nobody:/:/sbin/nologin [root@node4/app] # nmap-v-sP 192.168.137.0 up 24 | grep-B1'up 'Nmap scan report for 192.168.137.1 (192.168.137.1) Host is up (0.00089s latency).-- Nmap scan report for 192.168.137.6 (192.168.137.6) Host is up ( 0.00062s latency). [root@node4/app] # cat nmap.log | grep report | awk'{print $5} '192.168.137.1192.168.137.6

The relation of or expressed by grep-e:

Grep-e root-e bash

Filter words:

[root@node4/app] # echo "x-abc-y" | grep abc

X-abc-y

Man 7 regex

Character matching:. Match any single character [] match any single character within a specified range [^] match any single character [: alnum:] letters and numbers [: alpha:] outside the specified range represent any English uppercase and lowercase character Also known as Amurz Amurz [: lower:] lowercase letters [: upper:] uppercase letters [: blank:] white space characters (spaces and tabs) [: space:] horizontal and vertical white space characters (wider than [: blank:]) [: cntrl:] non-printable control characters (backspace, delete, Alarm bell.) [: digit:] decimal digits [: xdigit:] hexadecimal digits [: graph:] printable non-blank characters [: print:] printable characters [: punct:] punctuation matching times: used after the characters to be specified Used to specify the number of times the previous character will appear * match the previous character any number of times, including 0 greedy mode: match as long as possible. * any character of any length\? Match the character in front of it 0 or 1 times\ + match the character in front of it at least once\ {n\} match the character in front of it at least n times, at most n times\ {n, n\} match the previous character at most n times\ {n,\} match the previous character at least n times position anchor: locate the position where it appears ^ line first anchor The leftmost $line end anchor for the pattern, and the rightmost ^ PATTERN$ for the pattern matching entire line ^ $blank line ^ [[: space:]] * $blank line\

< 或 \b 词首锚定，用于单词模式的左侧\>

Or\ b suffix anchor; used to\ match the entire word on the right side of the word pattern

[root@node4~] # df | grep / dev/sd | grep-o "[0-9]\ +%" | grep-o "[0-9]\ +" | sort-nr | head-N1

twenty-nine

[root@node4~] # echo rootrbbt | grep "\ ([r.. t]\). *\ 1"

Rootrbbt

[root@node4~] # echo rootrbbt | grep "\ (r.. t\). *\ 1"

[root@node4~] # echo rootroot | grep "\ (r.. t\). *\ 1"

Rootroot

[root@node4~] # cat / etc/passwd | grep "^\ (. *\):. * /\ 1 $"

Sync:x:5:0:sync:/sbin:/bin/sync

Shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown

Halt:x:7:0:halt:/sbin:/sbin/halt

[root@node4~] # cat / etc/passwd | egrep "^ (. *):. * /\ 1 $"

Axy

[root@node4~] # echo axy | egrep "(a | b) xy"

Axy

[root@node4~] # cat / etc/redhat-release | grep-o "[0-9]\ +." | grep-o "[0-9]\ +"

seven

[root@node4~] # cat / etc/centos-release | grep-o "[0-9]\ +" | head-N1

seven

[root@node4~] # echo / etc/rc.d/init.d/ | egrep-o [^ /] * /? $

Init.d/

[root@node4~] # egrep-w "^ (root | sun)" / etc/passwd | cut-d:-F1 Magi 7

Root:/bin/bash

Sun:/bin/bash

Id address:

[0-9]

[1-9] [0-9]

1 [0-9] [0-9]

2 [0-4] [0-9]

25 [0-5]