sd_journal_get_cursor
systemd
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
Description
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_cursor3.
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
malloc3
and should be freed after use with
free3.
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_cursor3,
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_next3
(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
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
History
sd_journal_get_cursor() was added in version 187.
sd_journal_test_cursor() was added in version 195.
See Also
systemd1
sd-journal3
sd_journal_open3
sd_journal_seek_cursor3