Provided by: libsystemd-dev_229-4ubuntu21.31_amd64 

NAME
sd_booted - Test whether the system is running the systemd init system
SYNOPSIS
#include <systemd/sd-daemon.h>
int sd_booted(void);
DESCRIPTION
sd_booted() checks whether the system was booted up using the systemd init system.
RETURN VALUE
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.
NOTES
These APIs are implemented as a shared library, which can be compiled and linked to with the
libsystemd pkg-config(1) file.
Internally, this function checks whether the directory /run/systemd/system/ exists. A simple check like
this can also be implemented trivially in shell or any other language.
SEE ALSO
systemd(1), sd-daemon(3)
systemd 229 SD_BOOTED(3)