NAME
    Systemd::Util - Some utility routines related to Systemd

VERSION
    This document describes version 0.002 of Systemd::Util (from Perl
    distribution Systemd-Util), released on 2019-06-17.

FUNCTIONS
  systemd_is_running
    Usage:

     systemd_is_running() -> [status, msg, payload, meta]

    Check if systemd is running.

    Will return payload of 1 if systemd is running, 0 if not running,
    "undef" if cannot determine for sure. The result metadata "func.note"
    will give more details. The following heuristics are currently used:

    1. Check if "/sbin/init" exists, if it does not the return 0.
    2. Check if "/sbin/init" is a symlink to something with "systemd" in its
    name. If yes, then we return 1. We use Cwd's "realpath()" instead of
    "readlink()" here, to handle multiple redirection.
    3. Check if "/lib/systemd/systemd" exists. Return 0 otherwise.
    4. Check if "/sbin/init" is a hardlink to "/lib/systemd/systemd" by
    comparing its inode. Return 1 if it is.
    5. Return undef otherwise, since we detect that "/lib/systemd/systemd"
    exists (systemd is installed) but we cannot be sure if it is running or
    not.

    When used as a CLI, this routine will exit 0 if systemd is running, 1 if
    systemd is not running, or 99 if cannot determine for sure. To see the
    more detailed note, you can run the CLI with "--json" to return the
    whole enveloped response.

    This function is not exported by default, but exportable.

    No arguments.

    Returns an enveloped result (an array).

    First element (status) is an integer containing HTTP status code (200
    means OK, 4xx caller error, 5xx function error). Second element (msg) is
    a string containing error message, or 'OK' if status is 200. Third
    element (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (any)

HOMEPAGE
    Please visit the project's homepage at
    <https://metacpan.org/release/Systemd-Util>.

SOURCE
    Source repository is at
    <https://github.com/perlancar/perl-Systemd-Util>.

BUGS
    Please report any bugs or feature requests on the bugtracker website
    <https://rt.cpan.org/Public/Dist/Display.html?Name=Systemd-Util>

    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.

AUTHOR
    perlancar <perlancar@cpan.org>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2019 by 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.