man/sd_journal_open.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3         "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
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   8   Copyright 2012 Lennart Poettering
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  23
  24 <refentry id="sd_journal_open">
  25
  26         <refentryinfo>
  27                 <title>sd_journal_open</title>
  28                 <productname>systemd</productname>
  29
  30                 <authorgroup>
  31                         <author>
  32                                 <contrib>Developer</contrib>
  33                                 <firstname>Lennart</firstname>
  34                                 <surname>Poettering</surname>
  35                                 <email>lennart@poettering.net</email>
  36                         </author>
  37                 </authorgroup>
  38         </refentryinfo>
  39
  40         <refmeta>
  41                 <refentrytitle>sd_journal_open</refentrytitle>
  42                 <manvolnum>3</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>sd_journal_open</refname>
  47                 <refname>sd_journal_open_directory</refname>
  48                 <refname>sd_journal_close</refname>
  49                 <refpurpose>Open the system journal for reading</refpurpose>
  50         </refnamediv>
  51
  52         <refsynopsisdiv>
  53                 <funcsynopsis>
  54                         <funcsynopsisinfo>#include &lt;systemd/sd-journal.h&gt;</funcsynopsisinfo>
  55
  56                         <funcprototype>
  57                                 <funcdef>int <function>sd_journal_open</function></funcdef>
  58                                 <paramdef>sd_journal** <parameter>ret</parameter></paramdef>
  59                                 <paramdef>int <parameter>flags</parameter></paramdef>
  60                         </funcprototype>
  61
  62                         <funcprototype>
  63                                 <funcdef>int <function>sd_journal_open_directory</function></funcdef>
  64                                 <paramdef>sd_journal** <parameter>ret</parameter></paramdef>
  65                                 <paramdef>const char* <parameter>path</parameter></paramdef>
  66                                 <paramdef>int <parameter>flags</parameter></paramdef>
  67                         </funcprototype>
  68
  69                         <funcprototype>
  70                                 <funcdef>int <function>sd_journal_close</function></funcdef>
  71                                 <paramdef>sd_journal* <parameter>j</parameter></paramdef>
  72                         </funcprototype>
  73                 </funcsynopsis>
  74         </refsynopsisdiv>
  75
  76         <refsect1>
  77                 <title>Description</title>
  78
  79                 <para><function>sd_journal_open()</function> opens the
  80                 the log journal for reading. It will find all journal
  81                 files automatically and interleave them automatically
  82                 when reading. As first argument it takes a pointer to
  83                 a <literal>sd_journal</literal> pointer, which on
  84                 success will contain journal context afterwards. The
  85                 second argument is a flags field, which may consist of
  86                 the following flags ORed together:
  87                 <literal>SD_JOURNAL_LOCAL_ONLY</literal> makes sure
  88                 only journal files generated on the local machine will
  89                 be opened. <literal>SD_JOURNAL_RUNTIME_ONLY</literal>
  90                 makes sure only volatile journal files will be opened,
  91                 excluding those which are stored on persistant
  92                 storage. <literal>SD_JOURNAL_SYSTEM_ONLY</literal>
  93                 will ensure that only journal files of system services
  94                 and the kernel (in opposition to user session processes) will
  95                 be opened.</para>
  96
  97                 <para><function>sd_journal_open_directory()</function>
  98                 is similar to <function>sd_journal_open()</function>
  99                 but takes an absolute directory path as argument. All
 100                 journal files in this directory will be opened and
 101                 interleaved automatically. This call also takes a
 102                 flags argument, but it must be passed as 0 as no flags
 103                 are currently understood for this call.</para>
 104
 105                 <para><function>sd_journal_close()</function> will
 106                 close the journal context allocated with
 107                 <function>sd_journal_open()</function> or
 108                 <function>sd_journal_open_directory()</function> and
 109                 free its resources.</para>
 110
 111                 <para>When opening the journal only journal files
 112                 accessible to the calling user will be opened. If
 113                 journal files are not accessible to the caller this
 114                 will be silently ignored.</para>
 115
 116                 <para>See
 117                 <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 118                 for an example how to iterate through the journal
 119                 after opening it it with
 120                 <function>sd_journal_open()</function>.</para>
 121         </refsect1>
 122
 123         <refsect1>
 124                 <title>Return Value</title>
 125
 126                 <para>The <function>sd_journal_open()</function> and
 127                 <function>sd_journal_open_directory()</function> calls
 128                 return 0 on success or a negative errno-style error
 129                 code. <function>sd_journal_close()</function> returns
 130                 nothing.</para>
 131         </refsect1>
 132
 133         <refsect1>
 134                 <title>Notes</title>
 135
 136                 <para>The <function>sd_journal_open()</function>,
 137                 <function>sd_journal_open_directory()</function> and
 138                 <function>sd_journal_close()</function> interfaces are
 139                 available as shared library, which can be compiled and
 140                 linked to with the
 141                 <literal>libsystemd-journal</literal>
 142                 <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 143                 file.</para>
 144         </refsect1>
 145
 146         <refsect1>
 147                 <title>See Also</title>
 148
 149                 <para>
 150                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 151                         <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 152                         <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 153                         <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 154                 </para>
 155         </refsect1>
 156
 157 </refentry>