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sd_journal_get_realtime_usec(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | COLOPHON 

SD_JOURN...IME_USEC(3) sd_journal_get_realtime_usecSD_JOURN...IME_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 sd_journal_get_monotonic_usec().

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 is safe to allocate multiple independent objects and
       use each from a specific thread in parallel. However, it is 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
       do not 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),
       sd_journal_get_cutoff_realtime_usec(3)

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have a
       bug report for this manual page, see
       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2025-08-11.)  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
       man-pages@man7.org

systemd 258~rc2                                    SD_JOURN...IME_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)

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