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@UnitedWithCode
Forked from magnetikonline/README.md
Created October 10, 2022 07:34
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Bash string manipulation cheatsheet.

Bash string manipulation cheatsheet

Assignment
Assign value to variable if variable is not already set, value is returned.

Combine with a : no-op to discard/ignore return value.
${variable="value"}
: ${variable="value"}
Removal
Delete shortest match of needle from front of haystack ${haystack#needle}
Delete longest match of needle from front of haystack ${haystack##needle}
Delete shortest match of needle from back of haystack ${haystack%needle}
Delete longest match of needle from back of haystack ${haystack%%needle}
Replacement
Replace first match of needle with replacement from haystack ${haystack/needle/replacement}
Replace all matches of needle with replacement from haystack ${haystack//needle/replacement}
If needle matches front of haystack replace with replacement ${haystack/#needle/replacement}
If needle matches back of haystack replace with replacement ${haystack/%needle/replacement}
Substitution
If variable not set, return value, else variable ${variable-value}
If variable not set or empty, return value, else variable ${variable:-value}
If variable set, return value, else null string ${variable+value}
If variable set and not empty, return value, else null string ${variable:+value}
Extraction
Extract length characters from variable starting at position ${variable:position:length}
String length of variable ${#variable}
Escaping
Single quotes inside a single quoted string echo 'Don'\''t break my escape!'

Reference

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