System Services

Alpine Linux uses the OpenRC system for starting, stopping, and managing system services. This page explains how to work with OpenRC commands.

OpenRC Commands

Since Alpine Linux uses OpenRC instead of systemd, different commands are used to interact with system services. Instead of using the systemctl command, two separate commands are used:

1. rc-service, which allows services to be managed manually, and
2. rc-update, which allows services to be added or removed from runlevels.

For now, let’s focus on the rc-service command. In these examples, we’re going to use a fictional system service named foo. However, the command patterns below would apply to any service on the system by simply swapping the name of the service with foo in these examples. Typically, only the root user can start or stop services, so the commands to perform these steps would need to be prefixed with the doas command when running as a regular user.

Starting a Service

To start a service that has not yet been started, run:

rc-service foo start

Restarting a Service

If a service is already running but needs to be restarted, use:

rc-service foo restart

Stopping a Service

To stop a running service, execute:

rc-service foo stop

Checking Service Status

Not all services support status checks. However, many services do implement a status command and will respond to:

rc-service foo status

Listing all Running Services

A quick way to list all currently running services is to run:

rc-status

Runlevels

OpenRC automatically starts and stops configured services according to the system’s runlevel. Runlevels are useful on server systems for troubleshooting purposes, and it’s possible to add custom runlevels with OpenRC. However, the main runlevels that are available by default for configuring services on Alpine Linux are:

Most services are added to the default runlevel in Alpine Linux. However, a service can be added to (or removed from) another runlevel by specifying that runlevel in place of the word default in the following examples. We’ll continue to use the example service foo for the service name. Note that the default at the end of each of the first two commands can be omitted, since the default runlevel is implied (by default… hence the name).

Enabling a Service

To enable a service so that it starts as the system boots, run:

rc-update add foo default

Disabling a Service

To remove a service so that it isn’t started when the system boots, run:

rc-update del foo default

Listing All Services

To list the runlevel for all services that are configured for automatic execution, run:

rc-update

with no arguments. Note that this command lists only services that have been added to at least one runlevel.

To see all available services on the system, even ones that haven’t been added to a runlevel, run:

ls /etc/init.d

Log Files

Since Alpine Linux doesn’t use systemd, it also doesn’t use the binary log file format (the journal) that systemd imposes. Thus, instead of using journalctl to view logs, standard text file commands are instead run on files in the /var/log directory. Note that you generally need to be root to run these commands, which implies using doas when run as a regular user.

To see available log files, run:

ls /var/log

Some programs are configured to write to dedicated log files. To see the log output of these programs, substitute the log file name for /var/log/messages in the following examples. Programs that do not write to their own log files normally write to /var/log/messages instead.

Displaying Kernel Logs

To see kernel logs, run the command:

dmesg

On the console, most the output will scroll of the screen. To be able to read the whole output, pipe it through a pager like less:

dmesg | less

To search for a key word, use the grep command (this example searches for the word input):

dmesg | grep input

Displaying Application Logs

See the note above about substituting the file name for applications that write their own log files. In the general case, log messages can be viewed by running:

cat /var/log/messages

The same techniques for piping the output through a pager or grep can be used as shown above to allow the whole file to be used or to allow searching for a keyword.

Sometimes it is useful to watch the log messages as they occur, especially when debugging a server application:

tail -f /var/log/messages

To stop the display of log output and return to the command prompt, press CTRL+C.