Frequently asked questions for Systemd

How to check if 'systemctl daemon-reload' is needed

When systemd units are changed, a 'systemctl daemon-reload' might be needed. Need to know why? We can find the relevant units with some scripting.

How to check if a systemd service is enabled?

Systemd units can be enabled or disabled based on multiple factors, such as meeting specific dependencies. Learn how to see if a systemd service is enabled.

How to check if systemd is being used or active

Want to know if systemd is used on your Linux distribution? Learn how to quickly confirm that systemd is being used as your system and service manager.

How to clear systemd journal logs by time

Learn how to use the journalctl command to query the disk usage of the journal logs and how to clean or trim them by number, size, or age.

How to disable a systemd unit with systemctl

Want to disable a service or specific systemd unit? Use the systemctl command to configure units and disable it on boot or completely.

How to disable the background color of run0

The background color of run0, part of systemd, can be changed with the '--background' option. This way another color can be configured instead of its default.

How to limit the disk usage of the systemd journal

Learn how to define the maximum size that the systemd journal daemon may use on Linux systems for storing journals and limit its disk usage.

How to override the settings of a systemd unit

Systemd units have their own configuration file. The systemctl 'edit' command can be used to override settings of a systemd unit, including services.

How to reload or restart a systemd service?

Services that are controlled with systemd can be reloaded or restarted depending on their configuration. Use systemctl to perform the related restart tasks.

How to reload the systemd configuration

When changes are made to systemd unit files, such as service files, the systemd daemon needs to be reloaded. Use the daemon-reload subcommand to reload.

How to schedule a periodic task with systemd

Linux systems using systemd, use timers to schedule a repeating task. Learn how to configure these systemd timer units and fine-tune them.

How to see active systemd timers

Systemd timers are scheduled tasks for Linux systems. Show timer information with the systemctl command such as status, last execution, and its schedule.

How to see all active systemd units of one type

Linux systems using systemd have the systemctl command available to show all active systemd units of one particular type using the '--type' option.

How to see all enabled services with systemctl

Linux systems using systemd have the systemctl command available that can be used to show all service units, including a filter for only those that are enabled.

How to see all masked units with systemctl

Want to find all masked unit files on a Linux system running systemd? In this article we show how to do this with systemctl and query those units.

How to see kernel messages with journalctl

Linux systems using systemd store kernel events in the journal logs. Show these entries with the '--dmesg' or '-k' option, optionally with a date.

How to see logging for a specific unit or service

Linux systems with systemd store log entries in a journal. Limit the number of log entries from the journal by filtering journalctl output by unit.

How to see memory usage of a service with systemctl?

The systemctl command can be used to show the memory usage of a service managed by systemd. Use the subcommand 'status' to find the details about a unit.

How to see new log entries automatically with journalctl

Learn how to continuously show new log entries on Linux systems using systemd with the journalctl command. The behavior will be like the 'tail -f' command.

How to see only recent journal entries

Linux systems with systemd use journal to store log entries. Learn how to filter these journal entries by specifying a date or time interval.

How to see only running services with systemctl

Linux systems using systems may use the systemctl command to query services. Use a filter to reduce its output and only show all running services.

How to see the active settings of a systemd unit

Linux systems using systemd can use the systemctl command to show the all applied unit settings. This can be used on units like a service.

How to see the available systemd unit types

The systemctl command can be used to show all available systemd unit types. Here is how to find the available types and to select them.

How to see the dependencies of a systemd unit

The systemctl command has the list-dependencies option to show dependencies between units. But there are more options to query a little bit more information.

How to see the last X lines with journalctl

Limit the output from journalctl by defining the number of lines you want to see by using the '-n' option, optionally with the service itself.

How to see the size of the systemd journal

Use the journalctl command to show the size of the systemd journal logs. In this article we look how journalctl vacuuming works.

How to see the time synchronization details with timedatectl

Linux systems running systemd can use the timedatectl command to show time synchronization details. Learn how to use it, including its subcommands.

How to see which syscalls are part of a systemd syscall filter set

Systemd units can be filtered using the SystemCallFilter setting. Learn how to see what syscalls are part of a particular syscall filter set.

How to set environment variables in a systemd unit?

Systemd units can be configured to contain environment variables and passed along to the underlying application. Learn how to configure this unit setting.

How to show failed units with systemctl

Want to check the system for failed systemd units? In this article we show how to do this with systemctl and query the units with a failure state.

How to show the systemd machine ID

Linux systems using systemd store an unique identifier called the machine ID. Find this value using the hostnamectl command that comes with systemd.

How to start and enable a unit with systemctl

Systemd can start and enable a unit, such as a service at the same time. Learn how to use systemctl more efficiently to achieve this this action.

How to use systemctl edit to change a service?

Systemd allows customizing services with overrides. Learn how to edit an existing systemd service unit with the systemctl edit command.

How to verify a systemd unit for errors?

Learn how to troubleshoot issues with systemd units by verifying the unit files for any errors. One of the tools to help is systemd-analyze.

What does systemctl daemon-reload do?

When making changes to systemd unit files, you may need to use systemctl daemon-reload. This article explains why and what happens next.

What is a masked systemd unit?

Systemd units that are in a masked state are administratively disabled. While being in this state, they can not be started until they are unmasked.

What is a systemd unit?

Systemd units define resources, such as a service, path, socket, or timer. They are usually managed with the systemctl command.

What is systemd?

Systemd is a system and service manager on Linux distributions to start, stop, and monitor system services. Learn about systemd is and the main components.

What is the difference between systemctl disable and systemctl mask?

Want to disable a systemd service unit, but wondering the difference between systemctl disable and systemctl mask? This article explains the differences.

Why does systemctl list-units show units as 'not-found'?

Troubleshoot issues like units being marked as 'not-found' in the output of systemctl list-units. This articles help with the steps to take.