mirror of
https://github.com/systemd/systemd.git
synced 2024-11-23 02:03:37 +08:00
147 lines
6.6 KiB
XML
147 lines
6.6 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
|
|
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
|
|
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
|
|
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
|
|
|
|
<refentry id="sd_journal_seek_head" xmlns:xi="http://www.w3.org/2001/XInclude">
|
|
|
|
<refentryinfo>
|
|
<title>sd_journal_seek_head</title>
|
|
<productname>systemd</productname>
|
|
</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. to the
|
|
position before 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 position after the most recent available entry.</para>
|
|
|
|
<para><function>sd_journal_seek_monotonic_usec()</function> seeks to a position 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 a position 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 position 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.</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>
|
|
or an entry cursor be retrieved via
|
|
<citerefentry><refentrytitle>sd_journal_get_cursor</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>
|
|
|
|
<para>After the seek is done, and
|
|
<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
|
or a similar call has been made,
|
|
<citerefentry><refentrytitle>sd_journal_test_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
|
may be used to verify whether the newly selected entry actually matches the cursor.
|
|
</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>
|
|
|
|
<xi:include href="threads-aware.xml" xpointer="strict"/>
|
|
|
|
<xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>History</title>
|
|
<para><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> were added in version 187.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>See Also</title>
|
|
|
|
<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_next</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd_journal_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
</simplelist></para>
|
|
</refsect1>
|
|
|
|
</refentry>
|