systemd Developer Lennart Poettering lennart@poettering.net sd_journal_get_realtime_usec 3 sd_journal_get_realtime_usec sd_journal_get_monotonic_usec Read timestamps from the current journal entry #include <systemd/sd-journal.h> int sd_journal_get_realtime_usec sd_journal* j uint64_t* usec int sd_journal_get_monotonic_usec sd_journal* j uint64_t* usec sd_id128_t* boot_id sd_journal_get_realtime_usec() gets the realtime (wallclock) timestamp of the current journal entry. It takes two arguments: the journal context object and a pointer to a 64 Bit unsigned integer to store the timestamp in. The timestamp is in microseconds since the epoch, i.e. CLOCK_REALTIME. sd_journal_get_monotonic_usec() gets the monotonic timestamp of the current journal entry. It takes three arguments: the journal context object, a pointer to a 64 Bit unsigned integer to store the timestamp in as well as a 128 Bit ID buffer to store the boot ID of the monotonic timestamp in. The timestamp is in microseconds since boot-up of the specific boot, i.e. CLOCK_MONOTONIC. Since the monotonic clock begins new with every reboot it only defines a well-defined point in time when used together with an identifier identifying the boot, see sd_id128_get_boot3 for more information. If the boot ID parameter is passed NULL the function will fail if the monotonic timestamp of the current entry is not of the current system boot. Note that these functions will not work before sd_journal_next3 (or related call) has been called at least once, in order to position the read pointer at a valid entry. sd_journal_get_realtime_usec() and sd_journal_get_monotonic_usec() returns 0 on success or a negative errno-style error code. If the boot ID parameter was passed NULL and the monotonic timestamp of the current journal entry is not of the current system boot, -ESTALE is returned by sd_journal_get_monotonic_usec(). The sd_journal_get_realtime_usec() and sd_journal_get_monotonic_usec() interfaces are available as shared library, which can be compiled and linked to with the libsystemd-journal pkg-config1 file. systemd1, sd-journal3, sd_journal_open3, sd_journal_next3, sd_journal_get_data3, sd_id128_get_boot3, clock_gettime2, sd_journal_get_cutoff_realtime_usec3