<?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">
+ "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
+ SPDX-License-Identifier: LGPL-2.1+
+
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_seek_head">
- <refentryinfo>
- <title>sd_journal_seek_head</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_seek_head</refentrytitle>
- <manvolnum>3</manvolnum>
- </refmeta>
-
- <refnamediv>
- <refname>sd_journal_seek_head</refname>
- <refname>sd_journal_seek_tail</refname>
- <refname>sd_journal_seek_monotonic_usec</refname>
- <refname>sd_journal_seek_realtime_usec</refname>
- <refname>sd_journal_seek_cursor</refname>
- <refpurpose>Seek to a position in the
- journal</refpurpose>
- </refnamediv>
-
- <refsynopsisdiv>
- <funcsynopsis>
- <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
-
- <funcprototype>
- <funcdef>int <function>sd_journal_seek_head</function></funcdef>
- <paramdef>sd_journal* <parameter>j</parameter></paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>int <function>sd_journal_seek_tail</function></funcdef>
- <paramdef>sd_journal* <parameter>j</parameter></paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>int <function>sd_journal_seek_monotonic_usec</function></funcdef>
- <paramdef>sd_journal* <parameter>j</parameter></paramdef>
- <paramdef>sd_id128_t <parameter>boot_id</parameter></paramdef>
- <paramdef>uint64_t <parameter>usec</parameter></paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>int <function>sd_journal_seek_realtime_usec</function></funcdef>
- <paramdef>sd_journal* <parameter>j</parameter></paramdef>
- <paramdef>uint64_t <parameter>usec</parameter></paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>int <function>sd_journal_seek_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_seek_head()</function>
- seeks to the beginning of the journal, i.e. the oldest
- available entry.</para>
-
- <para>Similarly,
- <function>sd_journal_seek_tail()</function> may be
- used to seek to the end of the journal, i.e. the most
- recent available entry.</para>
-
- <para><function>sd_journal_seek_monotonic_usec()</function>
- seeks to the entry with the specified monotonic
- timestamp,
- i.e. <constant>CLOCK_MONOTONIC</constant>. Since
- monotonic time restarts on every reboot a boot ID
- needs to be specified as well.</para>
-
- <para><function>sd_journal_seek_realtime_usec()</function>
- seeks to the entry with the specified realtime
- (wallclock) timestamp,
- i.e. <constant>CLOCK_REALTIME</constant>. Note that
- the realtime clock is not necessarily monotonic. If a
- realtime timestamp is ambiguous, it is not defined
- which position is sought to.</para>
-
- <para><function>sd_journal_seek_cursor()</function>
- seeks to the entry located at the specified cursor
- string. For details on cursors, see
- <citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>. If
- no entry matching the specified cursor is found the
- call will seek to the next closest entry (in terms of
- time) instead. To verify whether the newly selected
- entry actually matches the cursor, use
- <citerefentry><refentrytitle>sd_journal_test_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
-
- <para>Note that these calls do not actually make any
- entry the new current entry, this needs to be done in
- a separate step with a subsequent
- <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- invocation (or a similar call). Only then, entry data
- may be retrieved via
- <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>. If
- no entry exists that matches exactly the specified
- seek address, the next closest is sought to. If
- <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- is used, the closest following entry will be sought to,
- if
- <citerefentry><refentrytitle>sd_journal_previous</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- is used the closest preceding entry is sought
- to.</para>
- </refsect1>
-
- <refsect1>
- <title>Return Value</title>
-
- <para>The functions return 0 on success or a negative
- errno-style error code.</para>
- </refsect1>
-
- <refsect1>
- <title>Notes</title>
-
- <para>The <function>sd_journal_seek_head()</function>,
- <function>sd_journal_seek_tail()</function>,
- <function>sd_journal_seek_monotonic_usec()</function>,
- <function>sd_journal_seek_realtime_usec()</function>,
- and <function>sd_journal_seek_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_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_journal_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- </para>
- </refsect1>
+ <refentryinfo>
+ <title>sd_journal_seek_head</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_seek_head</refentrytitle>
+ <manvolnum>3</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>sd_journal_seek_head</refname>
+ <refname>sd_journal_seek_tail</refname>
+ <refname>sd_journal_seek_monotonic_usec</refname>
+ <refname>sd_journal_seek_realtime_usec</refname>
+ <refname>sd_journal_seek_cursor</refname>
+ <refpurpose>Seek to a position in the
+ journal</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
+
+ <funcprototype>
+ <funcdef>int <function>sd_journal_seek_head</function></funcdef>
+ <paramdef>sd_journal *<parameter>j</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_journal_seek_tail</function></funcdef>
+ <paramdef>sd_journal *<parameter>j</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_journal_seek_monotonic_usec</function></funcdef>
+ <paramdef>sd_journal *<parameter>j</parameter></paramdef>
+ <paramdef>sd_id128_t <parameter>boot_id</parameter></paramdef>
+ <paramdef>uint64_t <parameter>usec</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_journal_seek_realtime_usec</function></funcdef>
+ <paramdef>sd_journal *<parameter>j</parameter></paramdef>
+ <paramdef>uint64_t <parameter>usec</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_journal_seek_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_seek_head()</function> seeks to the
+ beginning of the journal, i.e. the oldest available entry.</para>
+
+ <para>Similarly, <function>sd_journal_seek_tail()</function> may
+ be used to seek to the end of the journal, i.e. the most recent
+ available entry.</para>
+
+ <para><function>sd_journal_seek_monotonic_usec()</function> seeks
+ to the entry with the specified monotonic timestamp, i.e.
+ <constant>CLOCK_MONOTONIC</constant>. Since monotonic time
+ restarts on every reboot a boot ID needs to be specified as
+ well.</para>
+
+ <para><function>sd_journal_seek_realtime_usec()</function> seeks
+ to the entry with the specified realtime (wallclock) timestamp,
+ i.e. <constant>CLOCK_REALTIME</constant>. Note that the realtime
+ clock is not necessarily monotonic. If a realtime timestamp is
+ ambiguous, it is not defined which position is sought to.</para>
+
+ <para><function>sd_journal_seek_cursor()</function> seeks to the
+ entry located at the specified cursor string. For details on
+ cursors, see
+ <citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+ If no entry matching the specified cursor is found the call will
+ seek to the next closest entry (in terms of time) instead. To
+ verify whether the newly selected entry actually matches the
+ cursor, use
+ <citerefentry><refentrytitle>sd_journal_test_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
+
+ <para>Note that these calls do not actually make any entry the new
+ current entry, this needs to be done in a separate step with a
+ subsequent
+ <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ invocation (or a similar call). Only then, entry data may be
+ retrieved via
+ <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+ If no entry exists that matches exactly the specified seek
+ address, the next closest is sought to. If
+ <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ is used, the closest following entry will be sought to, if
+ <citerefentry><refentrytitle>sd_journal_previous</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ is used the closest preceding entry is sought to.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Return Value</title>
+
+ <para>The functions return 0 on success or a negative errno-style
+ error code.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Notes</title>
+
+ <para>All functions listed here are thread-agnostic and only a single thread may operate
+ on a given <structname>sd_journal</structname> object.</para>
+
+ <para>The <function>sd_journal_seek_head()</function>,
+ <function>sd_journal_seek_tail()</function>,
+ <function>sd_journal_seek_monotonic_usec()</function>,
+ <function>sd_journal_seek_realtime_usec()</function>,
+ and <function>sd_journal_seek_cursor()</function>
+ interfaces are available as a shared library, which can
+ be compiled and linked to with the
+ <constant>libsystemd</constant> <citerefentry project='die-net'><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_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_journal_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ </para>
+ </refsect1>
</refentry>
projects / thirdparty / systemd.git / blobdiff