5.1 KiB

Default Service Configuration

Pseudo Services

The default configuration contains a number of "pseudo services" in the boot target that don't actually do anything but are merely used as anchors in service dependencies, i.e. they indicate that some sort of milestone in the boot sequence has been reached. Everything that is part of that milestone specifies that it should be run before that pseudo service and everything that requires that this milestone has been reached, specifies that it wants to run afterwards.

The pseudo targets are (in the order that they are executed):

  • vfs

    All services that do mount point setup go before this, all service that depend on the fully mounted rootfs go after this.

  • sysinit

    The system has reached a sane state, i.e. the hostname is set, the system clock has a sane value, modules and kernel parameters are loaded, some very basic, fundamental services are running. Everything that is part of that setup process goes between vfs and sysinit, everything that requires a sane setup goes after sysinit.

  • network

    Network configuration is done. All services that do network configuration should position themselves between sysinit and network. Everything that requires a fully configured networking setup should go after network.

Default Bootup Services

This section outlines the services for the boot target that are enabled by default.

The following services are enabled by default and run before the vfs target for filesystem setup:

  • procfs - mount procfs to /proc and try to mount additional pseudo filesystems in /proc such as binfmt_misc
  • tmpfs - mount a tmpfs to /tmp
  • sysfs - mount sysfs to /sys and try to mount additional pseudo filesystems in /sys (e.g. securityfs, configfs, ...)
  • devfs - mount devtmpfs to /dev, try to mount additional pseudo filesystems in /dev (e.g. devpts, mqueue, ...) and try to create some additional device nodes and symlinks.
  • tmpfsvar - mount a tmpfs to /var and populate it with a default set of files and directories. Overlay mount /var/lib with lower dir on /cfg/preserve/var_lib/ and upper on /cfg/overlay/var_lib/.
  • tmpfsrun - mount a tmpfs to /run, symlink /var/run to /run and /var/lock to /run/lock.
  • mountusr - overlay mount setup for /usr. Lower dir is on /cfg/preserve/usr/ and upper on /cfg/overlay/usr/.

The following services are enabled by default and configured to run after the vfs target and before the sysinit target:

  • hostname - reload hostname /etc/hostname
  • loopback - bring the loopback device up
  • modules - iterate over the file /etc/modules and try to load each module using modprobe.
  • sysctl - restore kernel parameters using sysctl --system. See sysctl(8) for a list of possible locations that the parameters are read from.
  • usyslogd - Starts and supervises the usyslogd syslog implementation.
  • klogd - Starts and supervises the klogd daemon.

The following services are enabled by default and configured to run after the sysinit target and before the network target:

  • ifcfg - static network configuration Does the static network configuration outlined in

The following services are enabled by default and configured to run after the network target:

  • gcrond

Default Shutdown and Reboot Services

For the shutdown and reboot targets, the following services are executed:

  • sigterm - send the SIGTERM signal to all processes and wait for 5 seconds
  • sigkill - send the SIGKILL signal to all remaining processes
  • ifdown - bring all network interfaces down
  • sync - run the sync command

Additional Services not Enabled by Default

  • agetty - A parameterizeable, respawn type agetty service. The first parameter is the terminal device that the getty should run on.
  • consolefont - If enabled, run once before sysinit. Sets the console font to the first parameter.
  • dhcpcdmaster - If one or more network interfaces should be configured using dhcpcd, this service starts a central dhcpcd master instance.
  • dhcpcd - A parameterizeable single shot service that signals the dhcpcd master that it should configure a specific interface. The first parameter is the interface that should be configured by dhcpcd.
  • dnsmasq - A respawn type service for the dnsmasq DNS and DHCP server.
  • hostapd - If the system should operate a WIFI access point, this respawn type service can be enabled to manage an instace of the hostapd program.
  • unbound - A respawn type service that manages an instance of the unbound name resolver.
  • hwclock - If the system has a hardware clock, this service can restore the kernels clock from the hardware at bootup, between the vfs and sysinit targets.
  • nft - If enabled, restores net filter table rules during boot.
  • sshd_keygen - A wait type service that generates host keys for the OpenSSH server and then disables itself.
  • sshd - Starts an OpenSSH server after the network pseudo service and after the sshd_keygen service.
  • nginx - Starts the Nginx server after the network pseudo serivce.