sd_journal_seek_head - Man Page

#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​. 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​.

The functions return 0 on success or a negative errno-style error code​.

All functions listed here are thread-agnostic and only a single thread may operate on a given object at any given time​. Different threads may access the same object at different times​. Multiple independent objects may be used from different threads in parallel​.

Functions described here are available as a shared library, which can be compiled against and linked to with the libsystemd ​pkg-config(1) file​.

sd_journal_seek_head(), sd_journal_seek_tail(), sd_journal_seek_monotonic_usec(), sd_journal_seek_realtime_usec(), and sd_journal_seek_cursor() were added in version 187​.

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)

sd-journal(3), sd_journal_get_cursor(3), sd_journal_next(3), sd_journal_open(3), systemd.directives(7), systemd.index(7).

The man pages sd_journal_seek_cursor(3), sd_journal_seek_monotonic_usec(3), sd_journal_seek_realtime_usec(3) and sd_journal_seek_tail(3) are aliases of sd_journal_seek_head(3).