string-match - match substrings
===============================

Synopsis
--------

.. BEGIN SYNOPSIS

::

    string match [(-a | --all)] [(-e | --entire)] [(-i | --ignore-case)] [(-r | --regex)] [(-n | --index)] [(-q | --quiet)] [(-v | --invert)] PATTERN [STRING...]

.. END SYNOPSIS

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

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``string match`` tests each STRING against PATTERN and prints matching substrings. Only the first match for each STRING is reported unless ``-a`` or ``--all`` is given, in which case all matches are reported.

If you specify the ``-e`` or ``--entire`` then each matching string is printed including any prefix or suffix not matched by the pattern (equivalent to ``grep`` without the ``-o`` flag). You can, obviously, achieve the same result by prepending and appending ``*`` or ``.*`` depending on whether or not you have specified the ``--regex`` flag. The ``--entire`` flag is simply a way to avoid having to complicate the pattern in that fashion and make the intent of the ``string match`` clearer. Without ``--entire`` and ``--regex``, a PATTERN will need to match the entire STRING before it will be reported.

Matching can be made case-insensitive with ``--ignore-case`` or ``-i``.

If ``--index`` or ``-n`` is given, each match is reported as a 1-based start position and a length. By default, PATTERN is interpreted as a glob pattern matched against each entire STRING argument. A glob pattern is only considered a valid match if it matches the entire STRING.

If ``--regex`` or ``-r`` is given, PATTERN is interpreted as a Perl-compatible regular expression, which does not have to match the entire STRING. For a regular expression containing capturing groups, multiple items will be reported for each match, one for the entire match and one for each capturing group. With this, only the matching part of the STRING will be reported, unless ``--entire`` is given.

If ``--invert`` or ``-v`` is used the selected lines will be only those which do not match the given glob pattern or regular expression.

Exit status: 0 if at least one match was found, or 1 otherwise.

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Examples
--------

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Match Glob Examples
^^^^^^^^^^^^^^^^^^^

::

    >_ string match '?' a
    a

    >_ string match 'a*b' axxb
    axxb

    >_ string match -i 'a??B' Axxb
    Axxb

    >_ echo 'ok?' | string match '*\\?'
    ok?

    # Note that only the second STRING will match here.
    >_ string match 'foo' 'foo1' 'foo' 'foo2'
    foo

    >_ string match -e 'foo' 'foo1' 'foo' 'foo2'
    foo1
    foo
    foo2

    >_ string match 'foo?' 'foo1' 'foo' 'foo2'
    foo1
    foo
    foo2

Match Regex Examples
^^^^^^^^^^^^^^^^^^^^

::

    >_ string match -r 'cat|dog|fish' 'nice dog'
    dog

    >_ string match -r -v "c.*[12]" {cat,dog}(seq 1 4)
    dog1
    dog2
    cat3
    dog3
    cat4
    dog4

    >_ string match -r '(\\d\\d?):(\\d\\d):(\\d\\d)' 2:34:56
    2:34:56
    2
    34
    56

    >_ string match -r '^(\\w{{2,4}})\\g1$' papa mud murmur
    papa
    pa
    murmur
    mur

    >_ string match -r -a -n at ratatat
    2 2
    4 2
    6 2

    >_ string match -r -i '0x[0-9a-f]{{1,8}}' 'int magic = 0xBadC0de;'
    0xBadC0de

.. END EXAMPLES