sd_journal_seek_head, sd_journal_seek_tail, sd_journal_seek_monotonic_usec, sd_journal_seek_realtime_usec, sd_journal_seek_cursor — Seek to a position in the journal
|const char *cursor|
sd_journal_seek_head() seeks to the
beginning of the journal, i.e. the oldest available entry.
be used to seek to the end of the journal, i.e. the most recent
to the entry with the specified monotonic timestamp, i.e.
CLOCK_MONOTONIC. Since monotonic time
restarts on every reboot a boot ID needs to be specified as
to the entry with the specified realtime (wallclock) timestamp,
CLOCK_REALTIME. Note that the realtime
clock is not necessarily monotonic. If a realtime timestamp is
ambiguous, it is not defined which position is sought to.
sd_journal_seek_cursor() seeks to the
entry located at the specified cursor string. For details on
If no entry matching the specified cursor is found the call will
seek to the next closest entry (in terms of time) instead. To
verify whether the newly selected entry actually matches the
Note that these calls do not actually make any entry the new current entry, this needs to be done in a separate step with a subsequent sd_journal_next(3) invocation (or a similar call). Only then, entry data may be retrieved via sd_journal_get_data(3). If no entry exists that matches exactly the specified seek address, the next closest is sought to. If sd_journal_next(3) is used, the closest following entry will be sought to, if sd_journal_previous(3) is used the closest preceding entry is sought to.
The functions return 0 on success or a negative errno-style error code.
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.
These APIs are implemented as a shared
library, which can be compiled and linked to with the