systemctl-help

Show the manual page for a specific unit

$ systemctl help [unit]

$ systemctl help [unit1 unit2 ...]

$ systemctl help [unit] --user

$ systemctl help [unit] --no-pager

$ systemctl help [pid]

systemctl help [SUBCOMMAND]

SUBCOMMAND
    (Optional) The name of a specific systemctl subcommand for which to display more detailed help. If omitted, general help for all subcommands is shown.

The systemctl help command provides a concise summary of the usage of systemctl and its various subcommands. When invoked without any arguments, it lists all available systemctl subcommands along with a brief description for each. This serves as a quick reference for users to understand the basic functionality and syntax of the primary service management tool in systemd-based Linux distributions.

If a specific subcommand name is provided as an argument, systemctl help attempts to display more detailed information or a specific synopsis for that particular subcommand, aiding users in understanding its options and arguments. It's an essential first stop for exploring systemctl's capabilities without resorting to manual pages for every query.

The help output from systemctl help is often a summary. For comprehensive details, including all options, environment variables, and advanced usage, it is always recommended to consult the full manual page for systemctl using man systemctl or for specific subcommands, if available (e.g., man systemctl.unit for unit file syntax). The exact output and level of detail can vary slightly between systemd versions.

When run without arguments, systemctl help typically lists subcommands alphabetically, each followed by a one-line description. When a specific SUBCOMMAND is given, it usually prints the synopsis for that command.

While man systemctl provides the exhaustive documentation, systemctl help is designed for quick in-terminal assistance, focusing on common usage and subcommand discovery rather than deep dives into every flag and configuration option.

The systemctl command itself was introduced as part of the systemd init system, which gained widespread adoption in Linux distributions starting in the early 2010s (around 2011-2012). The help subcommand has been an integral part of systemctl from its early days, providing an accessible way for users to discover its extensive functionality. It reflects systemd's design philosophy of offering comprehensive control and introspection capabilities for system services and state.

systemctl(1), man(1), journalctl(1), loginctl(1), timedatectl(1)