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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | SEE ALSO | COLOPHON |
SD_JOURNAL_GET_CURSOR(3) sd_journal_get_cursor SD_JOURNAL_GET_CURSOR(3)
sd_journal_get_cursor, sd_journal_test_cursor - Get cursor string for
or test cursor string against the current journal entry
#include <systemd/sd-journal.h>
int sd_journal_get_cursor(sd_journal *j, char **cursor);
int sd_journal_test_cursor(sd_journal *j, const char *cursor);
sd_journal_get_cursor() returns a cursor string for the current
journal entry. A cursor is a serialization of the current journal
position formatted as text. The string only contains printable
characters and can be passed around in text form. The cursor
identifies a journal entry globally and in a stable way and may be
used to later seek to it via sd_journal_seek_cursor(3). The cursor
string should be considered opaque and not be parsed by clients.
Seeking to a cursor position without the specific entry being
available locally will seek to the next closest (in terms of time)
available entry. The call takes two arguments: a journal context
object and a pointer to a string pointer where the cursor string will
be placed. The string is allocated via libc malloc(3) and should be
freed after use with free(3).
Note that sd_journal_get_cursor() will not work before
sd_journal_next(3) (or related call) has been called at least once,
in order to position the read pointer at a valid entry.
sd_journal_test_cursor() may be used to check whether the current
position in the journal matches the specified cursor. This is useful
since cursor strings do not uniquely identify an entry: the same
entry might be referred to by multiple different cursor strings, and
hence string comparing cursors is not possible. Use this call to
verify after an invocation of sd_journal_seek_cursor(3) whether the
entry being sought to was actually found in the journal or the next
closest entry was used instead.
sd_journal_get_cursor() returns 0 on success or a negative
errno-style error code. sd_journal_test_cursor() returns positive if
the current entry matches the specified cursor, 0 if it does not
match the specified cursor or a negative errno-style error code on
failure.
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.
These APIs are implemented as a shared library, which can be compiled
and linked to with the libsystemd pkg-config(1) file.
systemd(1), sd-journal(3), sd_journal_open(3),
sd_journal_seek_cursor(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 2020-08-13. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2020-08-11.) 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 246 SD_JOURNAL_GET_CURSOR(3)
Pages that refer to this page: sd_journal_seek_cursor(3) , sd_journal_seek_head(3) , sd_journal_seek_monotonic_usec(3) , sd_journal_seek_realtime_usec(3) , sd_journal_seek_tail(3) , 30-systemd-environment-d-generator(7) , systemd.index(7)