String Patterns

String Operations

${varname#pattern} Remove up to the FIRST occurrence of the match from the beginning of the line

${varname##pattern} Remove up to the LAST occurrence of the match from the beginning of the line

${varname%pattern} Remove the FIRST occurrence of the match starting from the end of the line

${varname%%pattern} Remove the LAST occurrence of the match starting from the end of the line

${varname/pattern/string} Replace matching pattern with string

${varname/#pattern/string} Replace matching pattern at the BEGINNING of the line with string

${varname/%pattern/string} Replace matching pattern at the END of the line with string

${varname//pattern/string} Replace ALL matching occurrences of pattern with string

${varname:offset:length} Returns the substring of $varname starting at offset and up to the length of characters

${varname: ­length} Returns the substring of $varname starting at offset from the END

Variable Manipulations

${#varname} Get length of variable

${!pattern*} Indirect reference. Matches all variables names that match the pattern

${varname^} Transform first character of string to uppercase

${varname^^} Transform all characters of string to uppercase

${varname,} Transform first character of string to lowercase

${varname,,} Transform all characters of string to lowercase

Expansions to handle empty variables

${varname:­$var} If $varname isn't null return it's value, else return $var

${varname:=$var} If $varname isn't null return it's value, else assign it to $var and return it's value

${varname:?$var} If $varname isn't null return it's value, otherwise print varname: $var and abort

${varname:+$var} If $varname isn't null, return $var, otherwise return null

String Operations Examples

VAR="The quick brown fox jumped over the fox"

${VAR#*fox} jumped over the fox

${VAR%fox*} The quick brown fox jumped over the

${VAR%%fox*} The quick brown

${VAR/fox/dog} The quick brown dog jumped over the fox

${VAR//fox/dog} The quick brown dog jumped over the dog

${VAR/#The/A} A quick brown fox jumped over the fox

${VAR/%fox/dog} The quick brown fox jumped over the dog