151 lines
7.0 KiB
XML
151 lines
7.0 KiB
XML
<?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">
|
||
|
||
<!--
|
||
This file is part of systemd.
|
||
|
||
Copyright 2012 Lennart Poettering
|
||
|
||
systemd is free software; you can redistribute it and/or modify it
|
||
under the terms of the GNU Lesser General Public License as published by
|
||
the Free Software Foundation; either version 2.1 of the License, or
|
||
(at your option) any later version.
|
||
|
||
systemd is distributed in the hope that it will be useful, but
|
||
WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||
Lesser General Public License for more details.
|
||
|
||
You should have received a copy of the GNU Lesser General Public License
|
||
along with systemd; If not, see <http://www.gnu.org/licenses/>.
|
||
-->
|
||
|
||
<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 <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
|
||
<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 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>
|
||
|
||
<para>The <function>sd_journal_get_cursor()</function>
|
||
and <function>sd_journal_test_cursor()</function>
|
||
interfaces are available as a shared library, which can
|
||
be compiled and linked to with the
|
||
<constant>libsystemd</constant> <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>
|