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App-yamlsel-0.009
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NAME

yamlsel - Select YAML elements using CSel (CSS-selector-like) syntax

VERSION

This document describes version 0.009 of yamlsel (from Perl distribution App-yamlsel), released on 2024-07-11.

SYNOPSIS

% yamlsel file.yaml "Scalar[value > 3]"

OPTIONS

* marks required options.

Main options

--count

Shortcut for --node-action count.

See --node-action.

--dump

Shortcut for --node-action dump.

See --node-action.

--eval=s@

--eval E is shortcut for --action eval:E.

See --node-action.

Can be specified multiple times.

--expr=s

(No description)

Can also be specified as the 2nd command-line argument.

--file=s

Default value:

"-"

Can also be specified as the 1st command-line argument.

--node-action=s@

Specify action(s) to perform on matching nodes.

Default value:

["print_as_string"]

Each action can be one of the following:

  • count will print the number of matching nodes.

  • print_method will call on or more of the node object's methods and print the result. Example:

    print_method:as_string

  • dump will show a indented text representation of the node and its descendants. Each line will print information about a single node: its class, followed by the value of one or more attributes. You can specify which attributes to use in a dot-separated syntax, e.g.:

    dump:tag.id.class

    which will result in a node printed like this:

    HTML::Element tag=p id=undef class=undef

By default, if no attributes are specified, id is used. If the node class does not support the attribute, or if the value of the attribute is undef, then undef is shown.

  • eval will execute Perl code for each matching node. The Perl code will be called with arguments: ($node). For convenience, $_ is also locally set to the matching node. Example in htmlsel you can add this action:

    eval:'print $_->tag'

    which will print the tag name for each matching HTML::Element node.

Can be specified multiple times.

--node-actions-json=s

Specify action(s) to perform on matching nodes (JSON-encoded).

See --node-action.

--node-actions-on-descendants=s

Specify how descendants should be actioned upon.

Default value:

""

Valid values:

["","descendants_depth_first"]

This option sets how node action is performed (See node_actions option).

When set to '' (the default), then only matching nodes are actioned upon.

When set to 'descendants_depth_first', then after each matching node is actioned upon by an action, the descendants of the matching node are also actioned, in depth-first order. This option is sometimes necessary e.g. when your node's as_string() method shows a node's string representation that does not include its descendants.

--print

Shortcut for --node-action print_as_string.

See --node-action.

--print-method=s@

--print-method M is shortcut for --node-action print_method:M.

See --node-action.

Can be specified multiple times.

--root

Shortcut for --select-action=root.

See --select-action.

--select-action=s

Specify how we should select nodes.

Default value:

"csel"

Valid values:

["csel","root"]

The default is csel, which will select nodes from the tree using the CSel expression. Note that the root node itself is not included. For more details on CSel expression, refer to Data::CSel.

root will return a single node which is the root node.

-e=s@

-e E is shortcut for --action eval:E.

See --node-action.

Can be specified multiple times.

-R

Shortcut for --node-action-on-descendants=descendants_depth_first.

See --node-actions-on-descendants.

Output options

--format=s

Choose output format, e.g. json, text.

Default value:

undef

Output can be displayed in multiple formats, and a suitable default format is chosen depending on the application and/or whether output destination is interactive terminal (i.e. whether output is piped). This option specifically chooses an output format.

--json

Set output format to json.

--naked-res

When outputing as JSON, strip result envelope.

Default value:

0

By default, when outputing as JSON, the full enveloped result is returned, e.g.:

[200,"OK",[1,2,3],{"func.extra"=>4}]

The reason is so you can get the status (1st element), status message (2nd element) as well as result metadata/extra result (4th element) instead of just the result (3rd element). However, sometimes you want just the result, e.g. when you want to pipe the result for more post-processing. In this case you can use --naked-res so you just get:

[1,2,3]
--page-result

Filter output through a pager.

This option will pipe the output to a specified pager program. If pager program is not specified, a suitable default e.g. less is chosen.

--view-result

View output using a viewer.

This option will first save the output to a temporary file, then open a viewer program to view the temporary file. If a viewer program is not chosen, a suitable default, e.g. the browser, is chosen.

Other options

--help, -h, -?

Display help message and exit.

--version, -v

Display program's version and exit.

COMPLETION

This script has shell tab completion capability with support for several shells.

bash

To activate bash completion for this script, put:

complete -C yamlsel yamlsel

in your bash startup (e.g. ~/.bashrc). Your next shell session will then recognize tab completion for the command. Or, you can also directly execute the line above in your shell to activate immediately.

It is recommended, however, that you install modules using cpanm-shcompgen which can activate shell completion for scripts immediately.

tcsh

To activate tcsh completion for this script, put:

complete yamlsel 'p/*/`yamlsel`/'

in your tcsh startup (e.g. ~/.tcshrc). Your next shell session will then recognize tab completion for the command. Or, you can also directly execute the line above in your shell to activate immediately.

It is also recommended to install shcompgen (see above).

other shells

For fish and zsh, install shcompgen as described above.

HOMEPAGE

Please visit the project's homepage at https://metacpan.org/release/App-yamlsel.

SOURCE

Source repository is at https://github.com/perlancar/perl-App-yamlsel.

SEE ALSO

Data::CSel, Data::CSel::WrapStruct, CSel::Examples

jsonsel, a similar application but for selecting JSON elements.

orgsel, a similar application but for selecting Org elements.

htmlsel, a similar application but for selecting HTML elements using CSS selector syntax.

AUTHOR

perlancar <perlancar@cpan.org>

CONTRIBUTING

To contribute, you can send patches by email/via RT, or send pull requests on GitHub.

Most of the time, you don't need to build the distribution yourself. You can simply modify the code, then test via:

% prove -l

If you want to build the distribution (e.g. to try to install it locally on your system), you can install Dist::Zilla, Dist::Zilla::PluginBundle::Author::PERLANCAR, Pod::Weaver::PluginBundle::Author::PERLANCAR, and sometimes one or two other Dist::Zilla- and/or Pod::Weaver plugins. Any additional steps required beyond that are considered a bug and can be reported to me.

COPYRIGHT AND LICENSE

This software is copyright (c) 2024, 2020, 2019, 2016 by perlancar <perlancar@cpan.org>.

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

BUGS

Please report any bugs or feature requests on the bugtracker website https://rt.cpan.org/Public/Dist/Display.html?Name=App-yamlsel

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.