/ 
App-EmacsLockfileUtils-0.001
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/ emacs-lockfile-lock

NAME

emacs-lockfile-lock - Lock a file using Emacs-style lockfile

VERSION

This document describes version 0.001 of emacs-lockfile-lock (from Perl distribution App-EmacsLockfileUtils), released on 2025-03-13.

SYNOPSIS

emacs-lockfile-lock --help (or -h, -?)

emacs-lockfile-lock --version (or -v)

emacs-lockfile-lock [--force|-f|--no-force|--noforce] [--format=name|--json] [--(no)naked-res] [--page-result[=program]|--view-result[=program]] -- <target_file>

DESCRIPTION

Will return 412 if target file does not exist (unless force option is set to true, in which case we proceed to locking anyway).

Will return 304 if target file is already locked using Emacs-style lockfile by the same process as us.

Will return 409 if target file is already locked using Emacs-style lockfile by another process (unless when force option is set to true, in which case will take over the lock). Note that there are race conditions when using the force option (between checking that the lockfile, unlinking it, and creating our own). It is not recommended to use the force option.

Will return 500 if there's an error in reading the lockfile.

Will return 412 if we are not the same process that locks the file (unless force option is set to true, in which case we proceed to unlocking anyway).

Will return 500 if there's an error in removing the lockfile.

Will return 200 if everything goes ok.

OPTIONS

* marks required options.

Main options

--force, -f

(No description)

--target-file=s*

Target file.

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

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 emacs-lockfile-lock emacs-lockfile-lock

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 emacs-lockfile-lock 'p/*/`emacs-lockfile-lock`/'

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-EmacsLockfileUtils.

SOURCE

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

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) 2025 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-EmacsLockfileUtils

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.