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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | COLOPHON |
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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).
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.
Note that sd_journal_get_cursor() and sd_journal_test_cursor()
will not work before sd_journal_next(3) (or one of the other
functions which move to an entry) has been called at least once
to position the read pointer at a valid entry.
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.
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_get_cursor() was added in version 187.
sd_journal_test_cursor() was added in version 195.
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 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
[email protected]
systemd 257~devel SD_JOURNAL_GET_CURSOR(3)
Pages that refer to this page: sd-journal(3), sd_journal_next(3), sd_journal_open(3), sd_journal_seek_head(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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