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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | COLOPHON |
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SD_JOURNAL_SEEK_HEAD(3) sd_journal_seek_head SD_JOURNAL_SEEK_HEAD(3)
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. 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
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.
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)
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have
a bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2024-06-13.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 257~devel SD_JOURNAL_SEEK_HEAD(3)
Pages that refer to this page: sd-journal(3), sd_journal_get_cursor(3), sd_journal_next(3), sd_journal_open(3), systemd.directives(7), systemd.index(7)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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