# string-replace - replace substrings

## Synopsis

    string replace [-a | --all] [-f | --filter] [-i | --ignore-case]
                   [-r | --regex] [(-m | --max-matches) MAX] [-q | --quiet]
                   PATTERN REPLACEMENT [STRING ...]

## Description

`string replace` is similar to `string match` but replaces non-overlapping matching substrings with a replacement string and prints the result. By default, PATTERN is treated as a literal substring to be matched.

If -r or --regex is given, PATTERN is interpreted as a Perl-compatible regular expression, and REPLACEMENT can contain C-style escape sequences like t as well as references to capturing groups by number or name as $n or ${n}.

If you specify the -f or --filter flag then each input string is printed only if a replacement was done. This is useful where you would otherwise use this idiom: `a_cmd | string match pattern | string replace pattern new_pattern`. You can instead just write `a_cmd | string replace --filter pattern new_pattern`.

If --max-matches MAX or -m MAX is used, `string replace` will stop all processing after MAX lines of input have matched the specified pattern. In the event of `--filter` or `-f`, this means the output will be MAX lines in length. This can be used as an “early exit” optimization when processing long inputs but expecting a limited and fixed number of outputs that might be found considerably before the input stream has been exhausted.

Exit status: 0 if at least one replacement was performed, or 1 otherwise.

## Examples

### Replace Literal Examples

    >_ string replace is was 'blue is my favorite'
    blue was my favorite

    >_ string replace 3rd last 1st 2nd 3rd
    1st
    2nd
    last

    >_ string replace -a ' ' _ 'spaces to underscores'
    spaces_to_underscores

### Replace Regex Examples

    >_ string replace -r -a '[^\d.]+' ' ' '0 one two 3.14 four 5x'
    0 3.14 5

    >_ string replace -r '(\w+)\s+(\w+)' '$2 $1 $$' 'left right'
    right left $

    >_ string replace -r '\s*newline\s*' '\n' 'put a newline here'
    put a
    here