Systemd::Util - Some utility routines related to Systemd

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


     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

    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

    Return value: (any)

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    This software is copyright (c) 2019 by

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