<?xml version='1.0'?> <!--*-nxml-*-->

<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"

"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<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>

<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 &lt;systemd/sd-journal.h&gt;</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

<citerefentry><refentrytitle>malloc</refentrytitle><manvolnum>3</manvolnum></citerefentry>

and should be freed after use with

<citerefentry><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 seeked 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 doesn't match the specified

cursor or a negative errno-style error code on

failure.</para>

</refsect1>

<refsect1>

<title>Notes</title>

<para>The <function>sd_journal_get_cursor()</function>

and <function>sd_journal_test_cursor()</function>

interfaces are available as shared library, which can

be compiled and linked to with the

<literal>libsystemd-journal</literal>

<citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>

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>