Python full stack Linux base (partial) regular expression grep sed

/etc/profile

/etc/bashrc, variables are added to the shell environment and are permanently active.

/root/.bashrc

/root/.bash_profile

Regular expressions

Definition: a regular is a way to describe a character or string by combining symbols with special meanings, called regular expressions. (explained by the Order)

Three types of text processing tools/commands: grep sed awk

grep (filter)

Parameters

-n: Show Line numbers

-o: Show only matching content

-q: Silent mode, No output, you have to use $? to determine the success of the execution, that is, there is no filtering to the desired content

-l: if the match succeeds, only the file name is printed, the failure is not printed, USUALLY-RL together,

Grep-rl ' Root '/etc

-a: if the match succeeds, print the matching row and its subsequent n rows (commonly used for log files)

-b: if the match succeeds, the matching row and its first n rows are printed together

-c: if the match succeeds, the matching row and its n rows are printed together

-c: if the match succeeds, the number of rows to match is printed

-e: equals egrep, Extended

GREP-E = Egrep

-i: Ignore case, Direct output to search filter file

-v: inverse, mismatch

-w: matches the word consecutive letters, meets a space as a word processing

The regular introduction

^ Line beginning with * * * to filter lines (* for any Text)

End of line filter line ending with * * (* for any Text)

. Any single character other than the line break

* The preceding characters have 0 or infinitely

. * All Characters

[] any character within the character group \ denotes escape character, while-intelligence is placed at the beginning or end

[^] reverse each character within a character group (does not match each character in a group of Characters)
^[^] lines that begin with characters within a non-character group

[a-z] Lowercase Letter
[a-z] Capital Letters
[a-z] Lowercase and uppercase letters
[0-9] number
\< Word Header words are usually separated by spaces or special characters, consecutive strings are treated as words
\> Word tail

-v to filter out the files that need to be rejected.

Sed

Definition: Stream Editor Stream editer, which is a handler for the behavior unit

-n: Silent mode, No print output

-e: Specify extension rules

-i: making changes to files

-f: write ' rules to file

1. positioning: sed ' 3 ' test

2, d Delete sed ' 3d ' test: Delete line 3rd

3, p copy sed ' 3p ' test: print third line, (re-copy Output)

4, c change sed ' 3c ' 11111111 test: change the file on the third row

5, a append sed ' 3a ' 11111111 test: append files after the third line

6, i insert sed ' 3i ' 1111111 test: insert a row of files before the third Line.

Regular location and then the Write-only command is not positioned, All files are located within

Sed '/regular expression/command ' test

1, sed '/^root/d ' Test delete root this line;

Sed ' 1,3d ' test deletes 1 to 3 rows;

Sed ' 1d;3d ' test to delete the first and third rows

2, s command replace what to change what thing command: sed '///s ' file

Sed ' s/cd/234/' a.txt line matches to multiple, default only one

Sed ' s/cd/234/g ' a.txt line matches to multiple replacements

() to expand the code into a single whole

Sed-r extension regular, (default use!!!) ）

Sed-r '/^[0-9] ([a-z]{3) xsb$/s/sb/sb/g ' a.txt backwards and forwards from behind to understand

Replace the first word in the first line

Sed-r ' s/^ ([a-z]+) ([^a-z]+)/\1 \2/g ' test

1 Word symbols take the second part of the first part

Remove the Last Word

Sed-r ' s/([^a-z]) ([a-z]+) $/\1/g ' test

Two word swap locations

Sed-r ' s/^ ([a-z]+) ([^a-z]+) ([a-z]+] ([^a-z]+)/\3\2\1\4/g ' test

Python full stack Linux base (partial) regular expression grep sed