sd_booted — Test whether the system is running the systemd init system.
#include <systemd/sd-daemon.h>
int sd_booted( | void); |
On failure, this call returns a negative errno-style error code. If the system was booted up with systemd as init system, this call returns a positive return value, zero otherwise.
This function is provided by the reference implementation of APIs for new-style daemons and distributed with the systemd package. The algorithm it implements is simple, and can easily be reimplemented in daemons if it is important to support this interface without using the reference implementation.
Internally, this function checks whether the
/sys/fs/cgroup/systemd virtual file
system is mounted, by comparing the st_dev value of
the stat() data of
/sys/fs/cgroup and
/sys/fs/cgroup/systemd.
For details about the algorithm check the liberally licensed reference implementation sources: http://cgit.freedesktop.org/systemd/systemd/plain/src/sd-daemon.c resp. http://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-daemon.h
sd_booted() is implemented
in the reference implementation's
sd-daemon.c and
sd-daemon.h files. These
interfaces are available as shared library, which can
be compiled and linked to with the
libsystemd-daemon
pkg-config(1)
file. Alternatively, applications consuming these APIs
may copy the implementation into their source
tree. For more details about the reference
implementation see
sd_daemon(7).
If the reference implementation is used as drop-in files and -DDISABLE_SYSTEMD is set during compilation this function will always return 0 and otherwise become a NOP.