systemctl: System States, Shutdown and Poweroff Commands

│ │ ├──────────────┼─────────────────────────────────────────────────────────┼───────────┤ │ starting │ Late bootup, before the job queue becomes idle for the │ > 0 │ │ │ first time, or one of the rescue targets are reached. │ │ ├──────────────┼─────────────────────────────────────────────────────────┼───────────┤ │ running │ The system is fully operational. │ 0 │ ├──────────────┼─────────────────────────────────────────────────────────┼───────────┤ │ degraded │ The system is operational but one or more units failed. │ > 0 │ ├──────────────┼─────────────────────────────────────────────────────────┼───────────┤ │ maintenance │ The rescue or emergency target is active. │ > 0 │ ├──────────────┼─────────────────────────────────────────────────────────┼───────────┤ │ stopping │ The manager is shutting down. │ > 0 │ ├──────────────┼─────────────────────────────────────────────────────────┼───────────┤ │ offline │ The manager is not running. Specifically, this is the │ > 0 │ │ │ operational state if an incompatible program is running │ │ │ │ as system manager (PID 1). │ │ ├──────────────┼─────────────────────────────────────────────────────────┼───────────┤ │ unknown │ The operational state could not be determined, due to │ > 0 │ │ │ lack of resources or another error cause. │ │ └──────────────┴─────────────────────────────────────────────────────────┴───────────┘ default Enter default mode. This is equivalent to systemctl isolate default.target. This operation is blocking by default, use --no-block to request asynchronous behavior. rescue Enter rescue mode. This is equivalent to systemctl isolate rescue.target. This operation is blocking by default, use --no-block to request asynchronous behavior. emergency Enter emergency mode. This is equivalent to systemctl isolate emergency.target. This operation is blocking by default, use --no-block to request asynchronous behavior. halt Shut down and halt the system. This is mostly equivalent to systemctl start halt.target --job-mode=replace-irreversibly --no-block, but also prints a wall message to all users. This command is asynchronous; it will return after the halt operation is enqueued, without waiting for it to complete. Note that this operation will simply halt the OS kernel after shutting down, leaving the hardware powered on. Use systemctl poweroff for powering off the system (see below). If combined with --force, shutdown of all running services is skipped, however all processes are killed and all file systems are unmounted or mounted read-only, immediately followed by the system halt. If --force is specified twice, the operation is immediately executed without terminating any processes or unmounting any file systems. This may result in data loss. Note that when --force is specified twice the halt operation is executed by systemctl itself, and the system manager is not contacted. This means the command should succeed even when the system manager has crashed. poweroff Shut down and power-off the system. This is mostly equivalent to systemctl start poweroff.target --job-mode=replace-irreversibly --no-block, but also prints a wall message to all users. This command is asynchronous; it will return after the power-off operation is enqueued, without waiting for it to complete. If combined with --force, shutdown

This section details the different states of the system as reported by `is-system-running`, including 'stopping', 'offline', and 'unknown'. It also describes the `default`, `rescue`, and `emergency` commands for entering different modes. The `halt` and `poweroff` commands are explained for shutting down and halting or powering off the system, including options to force immediate shutdown.