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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 &lt;systemd/sd-journal.h&gt;</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

avilable entry.</para>

<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

which position is seeked 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>.</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 seeked to. If

<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>

is used the closest following entry will be seeked to,

if

<citerefentry><refentrytitle>sd_journal_previous</refentrytitle><manvolnum>3</manvolnum></citerefentry>

is used the closest preceeding entry is seeked

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>