NAME
    yq - Filter YAML through a command-line program

VERSION
    version 0.001

SYNOPSIS
        yq <filter>

        yq -h|--help

DESCRIPTION
    This program takes a stream of YAML documents on STDIN, applies a
    filter, then writes the results to STDOUT.

ARGUMENTS
  filter
    See "FILTER SYNTAX".

OPTIONS
FILTER SYNTAX
    .   Returns the entire document, unfiltered. Useful in if/then
        statements.

            # INPUT
            foo: bar
            baz: fuzz

            $ yq .
            foo: bar
            baz: fuzz

    .key
        Extract a single key out of a hash document.

            # INPUT
            foo: bar
            baz: fuzz

            $ yq .foo
            bar

    if lhs_filter eq rhs_filter then true_filter else false_filter
        If the lhs filter and rhs_filter are equal, return the true_filter,
        otherwise return the false_filter.

        For example

            # INPUT
            foo: bar
            baz: fuzz

            $ yq 'if .foo eq bar then .baz else .foo'
            fuzz

            $ yq 'if .foo eq buzz then .baz else .foo'
            bar

        The else false_filter is optional and defaults to returning
        undefined.

    empty
        The special value empty suppresses printing of a document. Normally,
        an undefined document will show up in the output as "--- ~". If your
        filter instead yields empty, the document will not be printed at
        all.

        This is especially useful in conditionals:

            # INPUT
            foo: bar
            baz: fuzz

            $ yq 'if .foo eq bar then . else empty'
            foo: bar
            baz: fuzz

            $ yq 'if .foo eq buzz then . else empty'
            $

    Values
        Any bareword that is not recognized as a syntax element is treated
        as a value.

SEE ALSO
    jq  <http://stedolan.github.io/jq/> A filter for JSON documents. The
        inspiration for this project.

AUTHOR
    Doug Bell <preaction@cpan.org>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2014 by Doug Bell.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.