mirror of
https://github.com/systemd/systemd-stable.git
synced 2024-12-24 21:34:08 +03:00
240 lines
10 KiB
XML
240 lines
10 KiB
XML
<?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">
|
||
|
||
<!--
|
||
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_open">
|
||
|
||
<refentryinfo>
|
||
<title>sd_journal_open</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_open</refentrytitle>
|
||
<manvolnum>3</manvolnum>
|
||
</refmeta>
|
||
|
||
<refnamediv>
|
||
<refname>sd_journal_open</refname>
|
||
<refname>sd_journal_open_directory</refname>
|
||
<refname>sd_journal_open_files</refname>
|
||
<refname>sd_journal_open_container</refname>
|
||
<refname>sd_journal_close</refname>
|
||
<refname>sd_journal</refname>
|
||
<refname>SD_JOURNAL_LOCAL_ONLY</refname>
|
||
<refname>SD_JOURNAL_RUNTIME_ONLY</refname>
|
||
<refname>SD_JOURNAL_SYSTEM</refname>
|
||
<refname>SD_JOURNAL_CURRENT_USER</refname>
|
||
<refpurpose>Open the system journal for reading</refpurpose>
|
||
</refnamediv>
|
||
|
||
<refsynopsisdiv>
|
||
<funcsynopsis>
|
||
<funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
|
||
|
||
<funcprototype>
|
||
<funcdef>int <function>sd_journal_open</function></funcdef>
|
||
<paramdef>sd_journal **<parameter>ret</parameter></paramdef>
|
||
<paramdef>int <parameter>flags</parameter></paramdef>
|
||
</funcprototype>
|
||
|
||
<funcprototype>
|
||
<funcdef>int <function>sd_journal_open_directory</function></funcdef>
|
||
<paramdef>sd_journal **<parameter>ret</parameter></paramdef>
|
||
<paramdef>const char *<parameter>path</parameter></paramdef>
|
||
<paramdef>int <parameter>flags</parameter></paramdef>
|
||
</funcprototype>
|
||
|
||
<funcprototype>
|
||
<funcdef>int <function>sd_journal_open_files</function></funcdef>
|
||
<paramdef>sd_journal **<parameter>ret</parameter></paramdef>
|
||
<paramdef>const char **<parameter>paths</parameter></paramdef>
|
||
<paramdef>int <parameter>flags</parameter></paramdef>
|
||
</funcprototype>
|
||
|
||
<funcprototype>
|
||
<funcdef>int <function>sd_journal_open_container</function></funcdef>
|
||
<paramdef>sd_journal **<parameter>ret</parameter></paramdef>
|
||
<paramdef>const char *<parameter>machine</parameter></paramdef>
|
||
<paramdef>int <parameter>flags</parameter></paramdef>
|
||
</funcprototype>
|
||
|
||
<funcprototype>
|
||
<funcdef>void <function>sd_journal_close</function></funcdef>
|
||
<paramdef>sd_journal *<parameter>j</parameter></paramdef>
|
||
</funcprototype>
|
||
</funcsynopsis>
|
||
</refsynopsisdiv>
|
||
|
||
<refsect1>
|
||
<title>Description</title>
|
||
|
||
<para><function>sd_journal_open()</function> opens the log journal
|
||
for reading. It will find all journal files automatically and
|
||
interleave them automatically when reading. As first argument it
|
||
takes a pointer to a <varname>sd_journal</varname> pointer, which,
|
||
on success, will contain a journal context object. The second
|
||
argument is a flags field, which may consist of the following
|
||
flags ORed together: <constant>SD_JOURNAL_LOCAL_ONLY</constant>
|
||
makes sure only journal files generated on the local machine will
|
||
be opened. <constant>SD_JOURNAL_RUNTIME_ONLY</constant> makes sure
|
||
only volatile journal files will be opened, excluding those which
|
||
are stored on persistent storage.
|
||
<constant>SD_JOURNAL_SYSTEM</constant> will cause journal files of
|
||
system services and the kernel (in opposition to user session
|
||
processes) to be opened.
|
||
<constant>SD_JOURNAL_CURRENT_USER</constant> will cause journal
|
||
files of the current user to be opened. If neither
|
||
<constant>SD_JOURNAL_SYSTEM</constant> nor
|
||
<constant>SD_JOURNAL_CURRENT_USER</constant> are specified, all
|
||
journal file types will be opened.</para>
|
||
|
||
<para><function>sd_journal_open_directory()</function> is similar
|
||
to <function>sd_journal_open()</function> but takes an absolute
|
||
directory path as argument. All journal files in this directory
|
||
will be opened and interleaved automatically. This call also takes
|
||
a flags argument, but it must be passed as 0 as no flags are
|
||
currently understood for this call.</para>
|
||
|
||
<para><function>sd_journal_open_files()</function> is similar to
|
||
<function>sd_journal_open()</function> but takes a
|
||
<constant>NULL</constant>-terminated list of file paths to open.
|
||
All files will be opened and interleaved automatically. This call
|
||
also takes a flags argument, but it must be passed as 0 as no
|
||
flags are currently understood for this call. Please note that in
|
||
the case of a live journal, this function is only useful for
|
||
debugging, because individual journal files can be rotated at any
|
||
moment, and the opening of specific files is inherently
|
||
racy.</para>
|
||
|
||
<para><function>sd_journal_open_container()</function> is similar
|
||
to <function>sd_journal_open()</function> but opens the journal
|
||
files of a running OS container. The specified machine name refers
|
||
to a container that is registered with
|
||
<citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
|
||
|
||
<para><varname>sd_journal</varname> objects cannot be used in the
|
||
child after a fork. Functions which take a journal object as an
|
||
argument (<function>sd_journal_next()</function> and others) will
|
||
return <constant>-ECHILD</constant> after a fork.
|
||
</para>
|
||
|
||
<para><function>sd_journal_close()</function> will close the
|
||
journal context allocated with
|
||
<function>sd_journal_open()</function> or
|
||
<function>sd_journal_open_directory()</function> and free its
|
||
resources.</para>
|
||
|
||
<para>When opening the journal only journal files accessible to
|
||
the calling user will be opened. If journal files are not
|
||
accessible to the caller, this will be silently ignored.</para>
|
||
|
||
<para>See
|
||
<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||
for an example of how to iterate through the journal after opening
|
||
it with <function>sd_journal_open()</function>.</para>
|
||
|
||
<para>A journal context object returned by
|
||
<function>sd_journal_open()</function> references a specific
|
||
journal entry as <emphasis>current</emphasis> entry, similar to a
|
||
file seek index in a classic file system file, but without
|
||
absolute positions. It may be altered with
|
||
<citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||
and
|
||
<citerefentry><refentrytitle>sd_journal_seek_head</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||
and related calls. The current entry position may be exported in
|
||
<emphasis>cursor</emphasis> strings, as accessible via
|
||
<citerefentry><refentrytitle>sd_journal_get_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
|
||
Cursor strings may be used to globally identify a specific journal
|
||
entry in a stable way and then later to seek to it (or if the
|
||
specific entry is not available locally, to its closest entry in
|
||
time)
|
||
<citerefentry><refentrytitle>sd_journal_seek_cursor</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
|
||
|
||
<para>Notification of journal changes is available via
|
||
<function>sd_journal_get_fd()</function> and related calls.</para>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Return Value</title>
|
||
|
||
<para>The <function>sd_journal_open()</function>,
|
||
<function>sd_journal_open_directory()</function>, and
|
||
<function>sd_journal_open_files()</function> calls return 0 on
|
||
success or a negative errno-style error code.
|
||
<function>sd_journal_close()</function> returns nothing.</para>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Notes</title>
|
||
|
||
<para>The <function>sd_journal_open()</function>,
|
||
<function>sd_journal_open_directory()</function> and
|
||
<function>sd_journal_close()</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>History</title>
|
||
|
||
<para><function>sd_journal_open()</function>,
|
||
<function>sd_journal_close()</function>,
|
||
<constant>SD_JOURNAL_LOCAL_ONLY</constant>,
|
||
<constant>SD_JOURNAL_RUNTIME_ONLY</constant>,
|
||
<constant>SD_JOURNAL_SYSTEM_ONLY</constant> were added in
|
||
systemd-38.</para>
|
||
|
||
<para><function>sd_journal_open_directory()</function> was added
|
||
in systemd-187.</para>
|
||
|
||
<para><constant>SD_JOURNAL_SYSTEM</constant>,
|
||
<constant>SD_JOURNAL_CURRENT_USER</constant>, and
|
||
<function>sd_journal_open_files()</function> were added in
|
||
systemd-205. <constant>SD_JOURNAL_SYSTEM_ONLY</constant> was
|
||
deprecated.</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_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd-machined</refentrytitle><manvolnum>8</manvolnum></citerefentry>
|
||
</para>
|
||
</refsect1>
|
||
|
||
</refentry>
|