Handling of shell strings

Handling strings in shell scripts

1, ${#变量名}

Function: Returns the length of a string

# foo= "This is a test"

# echo ${#foo}//Returns the length of the string foo

14

2. ${variable name: offset:length}

Function: Intercepts the string, length specifies the Intercept, or does not write; The index value of the first character of the string is 0

# foo= "ABCDEFG"

# echo ${foo:3:2}//from the Subscript 3 character start intercept, 2 total interception

De

# echo ${foo:3}//Start capturing the last character from the character subscript 3

Defg

3. ${variable name #pattern} ${variable name # #parttern}

Pattern: mode, wildcard expression

Function: Clears pattern-matching characters in a string

# foo= "File.txt.zip"

# echo ${foo#*.} A # symbol is cleared according to the shortest match

Txt.zip

# echo ${foo##*.} The 2 # symbol is cleared according to the longest match

Zip

4. ${variable name%pattern} ${variable name%%parttern}

Pattern: mode, wildcard expression

Function: Clears the pattern-matching character from the string and matches the string last

# echo $foo

File.txt.zip

# echo ${foo%.*}//1% stands according to shortest match

File.txt

# echo ${foo%%.*}//2-percent percent is represented by the longest match

File

5. String substitution operation

${variable name/old/new}

[Email protected] ~]# foo= "Mp3.txt.txt.mp3.avi"

[Email protected] ~]#

[[email protected] ~]# echo ${foo/txt/txt}

MP3. TXT.txt.mp3.avi

[Email protected] ~]#

[[email protected] ~]# echo ${foo//txt/txt}

MP3. Txt. TXT.mp3.avi

[Email protected] ~]# foo= "Txt.mp3.txt"

[Email protected] ~]#

[[email protected] ~]# echo ${foo/#txt/txt}

TXT.mp3.txt

[[email protected] ~]# echo ${foo/%txt/txt}

Txt.mp3.TXT

6, to achieve the conversion of uppercase and lowercase letters

# foo= "Abde"

# echo ${foo,,}//Convert string foo all to lowercase

Abde

# echo ${foo,}//Convert the 1th character of the string foo to lowercase

Abde

# echo ${foo^}//Converts the 1th character of a string foo to uppercase

Abde

# echo ${foo^^}//Convert string foo all to uppercase

Abde

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Handling of shell strings