Managing Services with 'systemd'
Photon OS manages services with systemd
. By using systemd
, Photon OS adopts a contemporary Linux standard to bootstrap the user space and concurrently start services. This is an architecture that differs from traditional Linux systems such as SUSE Linux Enterprise Server.
A traditional Linux system contains an initialization system called SysVinit. With SLES 11, for instance, the SysVinit-style init programs control how the system starts up and shuts down. Init implements system runlevels. A SysVinit runlevel defines a state in which a process or service runs.
In contrast to a SysVinit system, systemd
defines no such runlevels. Instead, systemd
uses a dependency tree of targets to determine which services to start when. Combined with the declarative nature of systemd
commands, systemd
targets reduce the amount of code needed to run a command, leaving you with code that is easier to maintain and probably faster to execute. For an overview of systemd
, see systemd System and Service Manager and the man page for systemd.
On Photon OS, you must manage services with systemd and systemctl
, its command-line utility for inspecting and controlling the system, and not the deprecated commands of init.d
.
For more information, see the index of all the systemd man pages, including systemctl, at https://www.freedesktop.org/software/systemd/man/