sd_journal_get_realtime_usec(3) — Linux manual page


SD_JOUR...ME_USEC(3)  sd_journal_get_realtime_usec  SD_JOUR...ME_USEC(3)

NAME         top

       sd_journal_get_realtime_usec, sd_journal_get_monotonic_usec -
       Read timestamps from the current journal entry

SYNOPSIS         top

       #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);

DESCRIPTION         top

       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. 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_boot(3) 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_next(3)
       (or related call) has been called at least once, in order to
       position the read pointer at a valid entry.

RETURN VALUE         top

       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

NOTES         top

       All functions listed here are thread-agnostic and only a single
       specific thread may operate on a given object during its entire
       lifetime. It's safe to allocate multiple independent objects and
       use each from a specific thread in parallel. However, it's not
       safe to allocate such an object in one thread, and operate or
       free it from any other, even if locking is used to ensure these
       threads don't operate on it at the very same time.

       Functions described here are available as a shared library, which
       can be compiled against and linked to with the
       libsystemd pkg-config(1) file.

HISTORY         top

       sd_journal_get_realtime_usec() and
       sd_journal_get_monotonic_usec() were added in version 187.

SEE ALSO         top

       systemd(1), sd-journal(3), sd_journal_open(3),
       sd_journal_next(3), sd_journal_get_data(3),
       sd_journal_get_seqnum(3), sd_id128_get_boot(3), clock_gettime(2),

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨⟩.  If you have
       a bug report for this manual page, see
       This page was obtained from the project's upstream Git repository
       ⟨⟩ on 2023-12-22.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2023-12-22.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

systemd 255                                         SD_JOUR...ME_USEC(3)

Pages that refer to this page: sd-journal(3)sd_journal_get_cutoff_realtime_usec(3)sd_journal_get_data(3)sd_journal_get_seqnum(3)sd_journal_next(3)sd_journal_seek_head(3)systemd.directives(7)systemd.index(7)