systemd Developer Lennart Poettering lennart@poettering.net sd_booted 3 sd_booted Test whether the system is running the systemd init system #include <systemd/sd-daemon.h> int sd_booted void sd_booted() checks whether the system was booted up using the systemd init system. 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 directory /run/systemd/system/ exists. A simple check like this can also be implemented trivially in shell or any other language. For details about the algorithm check the liberally licensed reference implementation sources: and sd_booted() is implemented in the reference implementation's sd-daemon.c and sd-daemon.h files. These interfaces are available as a shared library, which can be compiled and linked to with the libsystemd-daemon pkg-config1 file. Alternatively, applications consuming these APIs may copy the implementation into their source tree. For more details about the reference implementation see sd-daemon3. 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. systemd1, sd-daemon3