man/sd-journal.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->

<refentry id="sd-journal"
  xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>sd-journal</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>sd-journal</refentrytitle>
    <manvolnum>3</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>sd-journal</refname>
    <refpurpose>APIs for submitting and querying log entries to and
    from the journal</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcsynopsisinfo>#include &lt;systemd/sd-journal.h&gt;</funcsynopsisinfo>
    </funcsynopsis>

    <cmdsynopsis>
      <command>pkg-config --cflags --libs libsystemd</command>
    </cmdsynopsis>

  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><filename>sd-journal.h</filename> provides APIs to submit
    and query log entries. The APIs exposed act both as client for the
    <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    journal service and as parser for the journal files on disk.
    </para>

    <para>See
    <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
    <citerefentry><refentrytitle>sd_journal_stream_fd</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_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
    <citerefentry><refentrytitle>sd_journal_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
    <citerefentry><refentrytitle>sd_journal_seek_head</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
    <citerefentry><refentrytitle>sd_journal_enumerate_fields</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
    <citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
    <citerefentry><refentrytitle>sd_journal_get_cutoff_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
    <citerefentry><refentrytitle>sd_journal_get_cutoff_monotonic_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
    <citerefentry><refentrytitle>sd_journal_get_usage</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
    <citerefentry><refentrytitle>sd_journal_get_catalog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
    <citerefentry><refentrytitle>sd_journal_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
    <citerefentry><refentrytitle>sd_journal_has_runtime_files</refentrytitle><manvolnum>3</manvolnum></citerefentry>
    and
    <citerefentry><refentrytitle>sd_journal_has_persistent_files</refentrytitle><manvolnum>3</manvolnum></citerefentry>
    for more information about the functions implemented.</para>

    <para>Command line access for submitting entries to the journal is
    available with the
    <citerefentry><refentrytitle>systemd-cat</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    tool. Command line access for querying entries from the journal is
    available with the
    <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    tool.</para>
  </refsect1>

  <refsect1>
    <title>Thread safety</title>

    <para>Functions that operate on <structname>sd_journal</structname> objects are thread agnostic — given
    <structname>sd_journal</structname> pointer may only be used from one specific thread at all times (and it has to
    be the very same one during the entire lifetime of the object), but multiple, independent threads may use multiple,
    independent objects safely. Other functions — those that are used to send entries to the journal, like
    <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry> and similar,
    or those that are used to retrieve global information like
    <citerefentry><refentrytitle>sd_journal_stream_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry> and
    <citerefentry><refentrytitle>sd_journal_get_catalog_for_message_id</refentrytitle><manvolnum>3</manvolnum></citerefentry>
    — are fully thread-safe and may be called from multiple threads in parallel.</para>
  </refsect1>

  <xi:include href="libsystemd-pkgconfig.xml" />

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_journal_stream_fd</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_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_journal_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_journal_seek_head</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_journal_enumerate_fields</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_journal_get_cutoff_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_journal_get_cutoff_monotonic_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_journal_get_usage</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_journal_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_journal_query_unique</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_journal_get_catalog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_journal_has_runtime_files</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd_journal_has_persistent_files</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>