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<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
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available entry.</para>
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<para > Similar,
<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. CLOCK_MONOOTONIC. 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. CLOCK_REALTIME. Note that
the realtime clock is not necessary monotonic. If a
realtime timestamp is ambiguous it is not defined
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which position is sought to.</para>
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<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> .</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
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seek address the next closest is sought to. If
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<citerefentry > <refentrytitle > sd_journal_next</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry>
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is used the closest following entry will be sought to,
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if
<citerefentry > <refentrytitle > sd_journal_previous</refentrytitle> <manvolnum > 3</manvolnum> </citerefentry>
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is used the closest preceding entry is sought
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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 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_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>
