x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
SD_JOURNAL_SEEK_HEAD(3) sd_journal_seek_head SD_JOURNAL_SEEK_HEAD(3)
NAME
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
SYNOPSIS
#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);
DESCRIPTION
sd_journal_seek_head() seeks to the beginning of the journal, i.e. to
the position before the oldest available entry.
Similarly, sd_journal_seek_tail() may be used to seek to the end of the
journal, i.e. the position after the most recent available entry.
sd_journal_seek_monotonic_usec() seeks to a position 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 a position 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 position 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.
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) or an entry cursor be
retrieved via sd_journal_get_cursor(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.
After the seek is done, and sd_journal_next(3) or a similar call has
been made, sd_journal_test_cursor(3) may be used to verify whether the
newly selected entry actually matches the cursor.
RETURN VALUE
The functions return 0 on success or a negative errno-style error code.
NOTES
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 libsystemd pkg-config(1)
file.
SEE ALSO
systemd(1), sd-journal(3), sd_journal_open(3), sd_journal_next(3),
sd_journal_get_data(3), sd_journal_get_cursor(3),
sd_journal_get_realtime_usec(3)
systemd 254 SD_JOURNAL_SEEK_HEAD(3)
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