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Before: libsystemd-daemonpkg-config(1) After: libsystemd-daemon pkg-config(1) This fix is more complicated than it should be due to the consecutive XML elements separated by collapsible whitespace. Merging the lines and separating the XML elements with an en space or a non-breaking space is the only solution that results in one, and only one, space being inserted between them when testing. An em space results in two spaces being inserted.
151 lines
7.0 KiB
XML
151 lines
7.0 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2012 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="sd_journal_get_cursor">
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<refentryinfo>
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<title>sd_journal_get_cursor</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_journal_get_cursor</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_journal_get_cursor</refname>
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<refname>sd_journal_test_cursor</refname>
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<refpurpose>Get cursor string for or test cursor string against the current journal entry</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_journal_get_cursor</function></funcdef>
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<paramdef>sd_journal* <parameter>j</parameter></paramdef>
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<paramdef>char ** <parameter>cursor</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_journal_test_cursor</function></funcdef>
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<paramdef>sd_journal* <parameter>j</parameter></paramdef>
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<paramdef>const char * <parameter>cursor</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_journal_get_cursor()</function>
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returns a cursor string for the current journal
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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
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in text form. The cursor identifies a journal entry
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globally and in a stable way and may be used to later
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seek to it via
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<citerefentry><refentrytitle>sd_journal_seek_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>. The
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cursor string should be considered opaque and not be
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parsed by clients. Seeking to a cursor position
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without the specific entry being available locally
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will seek to the next closest (in terms of time)
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available entry. The call takes two arguments: a
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journal context object and a pointer to a string
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pointer where the cursor string will be placed. The
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string is allocated via libc
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<citerefentry><refentrytitle>malloc</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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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
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<function>sd_journal_get_cursor()</function> will not
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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
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order to position the read pointer at a valid
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entry.</para>
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<para><function>sd_journal_test_cursor()</function>
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may be used to check whether the current position in
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the journal matches the specified cursor. This is
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useful since cursor strings do not uniquely identify
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an entry: the same entry might be referred to by
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multiple different cursor strings, and hence string
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comparing cursors is not possible. Use this call to
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verify after an invocation of
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<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
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instead.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para><function>sd_journal_get_cursor()</function>
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returns 0 on success or a negative errno-style error
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code. <function>sd_journal_test_cursor()</function>
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returns positive if the current entry matches the
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specified cursor, 0 if it doesn't match the specified
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cursor or a negative errno-style error code on
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failure.</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>The <function>sd_journal_get_cursor()</function>
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and <function>sd_journal_test_cursor()</function>
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interfaces are available as shared library, which can
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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>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_journal_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_journal_seek_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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