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.
The sd_journal_seek_head(),
sd_journal_seek_tail(),
sd_journal_seek_monotonic_usec(),
sd_journal_seek_realtime_usec(),
and sd_journal_seek_cursor()
interfaces are available as a shared library, which can
be compiled and linked to with the
libsystemd pkg-config(1)
file.