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systemd/man/sd_journal_open.xml
Filipe Brandenburger 681eb9cf2b man: generate configured paths in manpages
In particular, use /lib/systemd instead of /usr/lib/systemd in distributions
like Debian which still have not adopted a /usr merge setup.

Use XML entities from man/custom-entities.ent to replace configured paths while
doing XSLT processing of the original XML files. There was precedent of some
files (such as systemd.generator.xml) which were already using this approach.

This addresses most of the (manual) fixes from this patch:
http://anonscm.debian.org/cgit/pkg-systemd/systemd.git/tree/debian/patches/Fix-paths-in-man-pages.patch?h=experimental-220

The idea of using generic XML entities was presented here:
http://lists.freedesktop.org/archives/systemd-devel/2015-May/032240.html

This patch solves almost all the issues, with the exception of:
- Path to /bin/mount and /bin/umount.
- Generic statements about preference of /lib over /etc.

These will be handled separately by follow up patches.

Tested:
- With default configure settings, ran "make install" to two separate
  directories and compared the output to confirm they matched exactly.
- Used a set of configure flags including $CONFFLAGS from Debian:
  http://anonscm.debian.org/cgit/pkg-systemd/systemd.git/tree/debian/rules
  Installed the tree and confirmed the paths use /lib/systemd instead of
  /usr/lib/systemd and that no other unexpected differences exist.
- Confirmed that `make distcheck` still passes.
2015-05-28 19:28:19 +02:00

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<?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" [
<!ENTITY % entities SYSTEM "custom-entities.ent" >
%entities;
]>
<!--
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 &lt;systemd/sd-journal.h&gt;</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>