[Shell] basic bash functions: wildcards and special symbols

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@ Blackeye poet <www. chenwei. ws>

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I. wildcard characters:

? MatchOneAny character.

* Match 0OneOrMultipleAny character.

[] Matching arbitrary in bracketsOneCharacter.

[-] Match anyOneCharacter,-indicates the range.

[^] Non-logical, matching is not in bracketsOneCharacter

 

The wildcard isUsed to match file namesOf:

Mkdir TMP;

Touch ABC;

Touch 0abc;

Touch ABCD;

Touch AABC;

 

Ls * ABC; # Matches ABC, 0abc, and AABC.

Ls * ABC *; # matching ABCD

Ls? ABC; # match 0ab, AABC

Ls [0-9] ABC; # match 0abc

Ls [^ 0-9] ABC; # match AABC

 

Ii. special symbols:

Single quotes (''): All special symbols in single quotes have no special meaning.

Double quotation marks (""): special characters in double quotation marks do not have special meanings. However"$", "'" And "\" have special meanings of "Call variable value", "reference command", and "Escape Character".

Backticks (''): The content enclosed by backticks isSystem commandsIn bash, It will be executed first. Like $ (), $ () is recommended, because it is very easy to read the quotation marks.

 

$ (): Used to reference system commands like anti-quotes.

 

#: In a shell script, the line starting with # represents a comment.

 

$: Value used to call a variableTo call the value of the variable name, you must use $ name to obtain the value of the variable.

 

\: Escape character. The special symbol following \ will lose its special meaning and become a common character. For example, \ $ outputs the "$" symbol, which is not a variable reference.

 

Name = www. chenwei. ws

Echo $ name # www. chenwei. ws

 

Echo '$ name' # $ name

Echo "$ name" # www. chenwei. ws

 

AB = 'date'

Echo $ AB # August 18, 2014 21:25:52 CST

Echo $ (date) # Monday, January 1, August 18, 2014 21:25:52 CST