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<refentry id= "sd_journal_get_cursor" >
<refentryinfo >
<title > sd_journal_get_cursor</title>
<productname > systemd</productname>
<authorgroup >
<author >
<contrib > Developer</contrib>
<firstname > Lennart</firstname>
<surname > Poettering</surname>
<email > lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta >
<refentrytitle > sd_journal_get_cursor</refentrytitle>
<manvolnum > 3</manvolnum>
</refmeta>
<refnamediv >
<refname > sd_journal_get_cursor</refname>
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<refname > sd_journal_test_cursor</refname>
<refpurpose > Get cursor string for or test cursor string against the current journal entry</refpurpose>
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</refnamediv>
<refsynopsisdiv >
<funcsynopsis >
<funcsynopsisinfo > #include < systemd/sd-journal.h> </funcsynopsisinfo>
<funcprototype >
<funcdef > int <function > sd_journal_get_cursor</function> </funcdef>
<paramdef > sd_journal* <parameter > j</parameter> </paramdef>
<paramdef > char ** <parameter > cursor</parameter> </paramdef>
</funcprototype>
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<funcprototype >
<funcdef > int <function > sd_journal_test_cursor</function> </funcdef>
<paramdef > sd_journal* <parameter > j</parameter> </paramdef>
<paramdef > const char * <parameter > cursor</parameter> </paramdef>
</funcprototype>
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</funcsynopsis>
</refsynopsisdiv>
<refsect1 >
<title > Description</title>
<para > <function > sd_journal_get_cursor()</function>
returns a cursor string for the current journal
entry. A cursor is a serialization of the current
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journal position formatted as text. The string only
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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
<citerefentry > <refentrytitle > sd_journal_seek_cursor</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry> . 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
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journal context object and a pointer to a string
pointer where the cursor string will be placed. The
string is allocated via libc
<citerefentry > <refentrytitle > malloc</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry>
and should be freed after use with
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<citerefentry > <refentrytitle > free</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry> .</para>
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<para > Note that
<function > sd_journal_get_cursor()</function> will not
work before
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<citerefentry > <refentrytitle > sd_journal_next</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry>
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(or related call) has been called at least once, in
order to position the read pointer at a valid
entry.</para>
<para > <function > sd_journal_test_cursor()</function>
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
<citerefentry > <refentrytitle > sd_journal_seek_cursor</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry>
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whether the entry being sought to was actually found
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in the journal or the next closest entry was used
instead.</para>
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</refsect1>
<refsect1 >
<title > Return Value</title>
<para > <function > sd_journal_get_cursor()</function>
returns 0 on success or a negative errno-style error
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code. <function > sd_journal_test_cursor()</function>
returns positive if the current entry matches the
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specified cursor, 0 if it does not match the specified
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cursor or a negative errno-style error code on
failure.</para>
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</refsect1>
<refsect1 >
<title > Notes</title>
<para > The <function > sd_journal_get_cursor()</function>
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and <function > sd_journal_test_cursor()</function>
interfaces are available as shared library, which can
be compiled and linked to with the
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<constant > libsystemd-journal</constant> <citerefentry > <refentrytitle > pkg-config</refentrytitle> <manvolnum > 1</manvolnum> </citerefentry>
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file.</para>
</refsect1>
<refsect1 >
<title > See Also</title>
<para >
<citerefentry > <refentrytitle > systemd</refentrytitle> <manvolnum > 1</manvolnum> </citerefentry> ,
<citerefentry > <refentrytitle > sd-journal</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry> ,
<citerefentry > <refentrytitle > sd_journal_open</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry> ,
<citerefentry > <refentrytitle > sd_journal_seek_cursor</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry>
</para>
</refsect1>
</refentry>
