string-replace - replace substrings
===================================

Synopsis
--------

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.. synopsis::

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

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Description
-----------

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``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.

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Examples
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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

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