Replace substring in a string

Pattern expansion

To replace the first occurance of a substring into a string:

${input_variable_name/search_string/replacement}

To replace all occurances of a substring into a string:

${input_variable_name//search_string/replacement}

Examples

Following example substitues the first occurance of the pattern. In this case the character a is being replaced by dash -:

$ the_input=baobab
$ echo ${the_input/a/-}
b-obab

Similarly we could replace all occurencies of the pattern:

$ the_input=baobab
$ echo ${the_input//a/-}
b-ob-b

Here we illustrated only simple string replacement. It is possible to use patterns. For details, refer to Shell Parameter Expansion.

See also