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<!-- SPDX - License - Identifier: LGPL - 2.1 - or - later -->
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<refentry id= "sd_journal_get_cursor" xmlns:xi= "http://www.w3.org/2001/XInclude" >
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<refentryinfo >
<title > sd_journal_get_cursor</title>
<productname > systemd</productname>
</refentryinfo>
<refmeta >
<refentrytitle > sd_journal_get_cursor</refentrytitle>
<manvolnum > 3</manvolnum>
</refmeta>
<refnamediv >
<refname > sd_journal_get_cursor</refname>
<refname > sd_journal_test_cursor</refname>
<refpurpose > Get cursor string for or test cursor string against the current journal entry</refpurpose>
</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>
<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>
</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 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
<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 journal
context object and a pointer to a string pointer where the cursor
string will be placed. The string is allocated via libc
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<citerefentry project= 'man-pages' > <refentrytitle > malloc</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry>
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and should be freed after use with
<citerefentry project= 'man-pages' > <refentrytitle > free</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry> .</para>
<para > Note that <function > sd_journal_get_cursor()</function> will
not work before
<citerefentry > <refentrytitle > sd_journal_next</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry>
(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>
whether the entry being sought to was actually found
in the journal or the next closest entry was used
instead.</para>
</refsect1>
<refsect1 >
<title > Return Value</title>
<para > <function > sd_journal_get_cursor()</function> returns 0 on
success or a negative errno-style error code.
<function > sd_journal_test_cursor()</function> 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.</para>
</refsect1>
<refsect1 >
<title > Notes</title>
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<xi:include href= "threads-aware.xml" xpointer= "strict" />
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<xi:include href= "libsystemd-pkgconfig.xml" xpointer= "pkgconfig-text" />
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</refsect1>
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<refsect1 >
<title > History</title>
<para > <function > sd_journal_get_cursor()</function> was added in version 187.</para>
<para > <function > sd_journal_test_cursor()</function> was added in version 195.</para>
</refsect1>
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<refsect1 >
<title > See Also</title>
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<para > <simplelist type= "inline" >
<member > <citerefentry > <refentrytitle > systemd</refentrytitle> <manvolnum > 1</manvolnum> </citerefentry> </member>
<member > <citerefentry > <refentrytitle > sd-journal</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry> </member>
<member > <citerefentry > <refentrytitle > sd_journal_open</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry> </member>
<member > <citerefentry > <refentrytitle > sd_journal_seek_cursor</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry> </member>
</simplelist> </para>
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</refsect1>
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</refentry>