sd_journal_get_realtime_usec, sd_journal_get_monotonic_usec — Read timestamps from the current journal entry
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.
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,
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
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
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.
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
-ESTALE is returned by
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
sd_journal_get_monotonic_usec() were added in version 187.