sd_journal_get_cursor(3) — Linux manual page


SD_JOURNAL_GET_CURSOR(3)  sd_journal_get_cursor SD_JOURNAL_GET_CURSOR(3)

NAME         top

       sd_journal_get_cursor, sd_journal_test_cursor - Get cursor string
       for or test cursor string against the current journal entry

SYNOPSIS         top

       #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);

DESCRIPTION         top

       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

       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.

RETURN VALUE         top

       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.

NOTES         top

       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.

HISTORY         top

       sd_journal_get_cursor() was added in version 187.

       sd_journal_test_cursor() was added in version 195.

SEE ALSO         top

       systemd(1), sd-journal(3), sd_journal_open(3),

COLOPHON         top

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       manager) project.  Information about the project can be found at
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       This page was obtained from the project's upstream Git repository
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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)