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
#include <systemd/sd-journal.h>
int sd_journal_seek_head( | sd_journal *j); |
int sd_journal_seek_tail( | sd_journal *j); |
int sd_journal_seek_monotonic_usec( | sd_journal *j, |
| sd_id128_t boot_id, | |
uint64_t usec); |
int sd_journal_seek_realtime_usec( | sd_journal *j, |
uint64_t usec); |
int sd_journal_seek_cursor( | sd_journal *j, |
const char *cursor); |
sd_journal_seek_head() seeks to the
beginning of the journal, i.e. the oldest available entry.
Similarly, sd_journal_seek_tail() may
be used to seek to the end of the journal, i.e. the most recent
available entry.
sd_journal_seek_monotonic_usec() seeks
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
well.
sd_journal_seek_realtime_usec() seeks
to the entry with the specified realtime (wallclock) timestamp,
i.e. 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
cursors, see
sd_journal_get_cursor(3).
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
cursor, use
sd_journal_test_cursor(3).
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.
All functions listed here are thread-agnostic and only a single thread may operate on a given sd_journal object.
These APIs are implemented as a shared
library, which can be compiled and linked to with the
libsystemd pkg-config(1)
file.