mirror of
https://github.com/systemd/systemd.git
synced 2024-12-27 07:22:31 +03:00
185 lines
8.8 KiB
XML
185 lines
8.8 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
|
|
<!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_query_unique" xmlns:xi="http://www.w3.org/2001/XInclude">
|
|
|
|
<refentryinfo>
|
|
<title>sd_journal_query_unique</title>
|
|
<productname>systemd</productname>
|
|
</refentryinfo>
|
|
|
|
<refmeta>
|
|
<refentrytitle>sd_journal_query_unique</refentrytitle>
|
|
<manvolnum>3</manvolnum>
|
|
</refmeta>
|
|
|
|
<refnamediv>
|
|
<refname>sd_journal_query_unique</refname>
|
|
<refname>sd_journal_enumerate_unique</refname>
|
|
<refname>sd_journal_enumerate_available_unique</refname>
|
|
<refname>sd_journal_restart_unique</refname>
|
|
<refname>SD_JOURNAL_FOREACH_UNIQUE</refname>
|
|
<refpurpose>Read unique data fields from the journal</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_journal_query_unique</function></funcdef>
|
|
<paramdef>sd_journal *<parameter>j</parameter></paramdef>
|
|
<paramdef>const char *<parameter>field</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_journal_enumerate_available_unique</function></funcdef>
|
|
<paramdef>sd_journal *<parameter>j</parameter></paramdef>
|
|
<paramdef>const void **<parameter>data</parameter></paramdef>
|
|
<paramdef>size_t *<parameter>length</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_journal_enumerate_unique</function></funcdef>
|
|
<paramdef>sd_journal *<parameter>j</parameter></paramdef>
|
|
<paramdef>const void **<parameter>data</parameter></paramdef>
|
|
<paramdef>size_t *<parameter>length</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>void <function>sd_journal_restart_unique</function></funcdef>
|
|
<paramdef>sd_journal *<parameter>j</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef><function>SD_JOURNAL_FOREACH_UNIQUE</function></funcdef>
|
|
<paramdef>sd_journal *<parameter>j</parameter></paramdef>
|
|
<paramdef>const void *<parameter>data</parameter></paramdef>
|
|
<paramdef>size_t <parameter>length</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsect1>
|
|
<title>Description</title>
|
|
|
|
<para><function>sd_journal_query_unique()</function> queries the journal for all unique values the
|
|
specified field can take. It takes two arguments: the journal to query and the field name to look
|
|
for. Well-known field names are listed on
|
|
<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
|
|
but any field can be specified. Field names must be specified without a trailing
|
|
<literal>=</literal>. After this function has been executed successfully the field values may be queried
|
|
using <function>sd_journal_enumerate_unique()</function> and
|
|
<function>sd_journal_enumerate_available_unique()</function>. Invoking one of those calls will change the
|
|
field name being queried and reset the enumeration index to the first field value that matches.</para>
|
|
|
|
<para><function>sd_journal_enumerate_unique()</function> may be used to iterate through all data fields
|
|
which match the previously selected field name as set with
|
|
<function>sd_journal_query_unique()</function>. On each invocation the next field data matching the field
|
|
name is returned. The order of the returned data fields is not defined. It takes three arguments: the
|
|
journal object, plus a pair of pointers to pointer/size variables where the data object and its size
|
|
shall be stored. The returned data is in a read-only memory map and is only valid until the next
|
|
invocation of <function>sd_journal_enumerate_unique()</function>. Note that the data returned will be
|
|
prefixed with the field name and <literal>=</literal>. Note that this call is subject to the data field
|
|
size threshold as controlled by <function>sd_journal_set_data_threshold()</function> and only the initial
|
|
part of the field up to the threshold is returned. An error is returned for fields which cannot be
|
|
retrieved. See the error list below for details.</para>
|
|
|
|
<para><function>sd_journal_enumerate_available_unique()</function> is similar to
|
|
<function>sd_journal_enumerate_unique()</function>, but silently skips any fields which may be valid, but
|
|
are too large or not supported by current implementation.</para>
|
|
|
|
<para><function>sd_journal_restart_unique()</function> resets the
|
|
data enumeration index to the beginning of the list. The next
|
|
invocation of <function>sd_journal_enumerate_unique()</function>
|
|
will return the first field data matching the field name
|
|
again.</para>
|
|
|
|
<para>Note that the <function>SD_JOURNAL_FOREACH_UNIQUE()</function> macro may be used as a handy wrapper
|
|
around <function>sd_journal_restart_unique()</function> and
|
|
<function>sd_journal_enumerate_available_unique()</function>.</para>
|
|
|
|
<para>Note that these functions currently are not influenced by
|
|
matches set with <function>sd_journal_add_match()</function> but
|
|
this might change in a later version of this software.</para>
|
|
|
|
<para>To enumerate all field names currently in use (and thus all suitable field parameters for
|
|
<function>sd_journal_query_unique()</function>), use the
|
|
<citerefentry><refentrytitle>sd_journal_enumerate_fields</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
|
call.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Return Value</title>
|
|
|
|
<para><function>sd_journal_query_unique()</function> returns 0 on success or a negative errno-style error
|
|
code. <function>sd_journal_enumerate_unique()</function> and
|
|
<function>sd_journal_query_available_unique()</function> return a positive integer if the next field data
|
|
has been read, 0 when no more fields remain, or a negative errno-style error code.
|
|
<function>sd_journal_restart_unique()</function> doesn't return anything.</para>
|
|
|
|
<refsect2>
|
|
<title>Errors</title>
|
|
|
|
<para>Returned errors may indicate the following problems:</para>
|
|
|
|
<variablelist>
|
|
<xi:include href="sd_journal_get_data.xml" xpointer="EINVAL"/>
|
|
<xi:include href="sd_journal_get_data.xml" xpointer="ECHILD"/>
|
|
<xi:include href="sd_journal_get_data.xml" xpointer="EADDRNOTAVAIL"/>
|
|
<xi:include href="sd_journal_get_data.xml" xpointer="ENOENT"/>
|
|
<xi:include href="sd_journal_get_data.xml" xpointer="ENOBUFS"/>
|
|
<xi:include href="sd_journal_get_data.xml" xpointer="E2BIG"/>
|
|
<xi:include href="sd_journal_get_data.xml" xpointer="EPROTONOSUPPORT"/>
|
|
<xi:include href="sd_journal_get_data.xml" xpointer="EBADMSG"/>
|
|
<xi:include href="sd_journal_get_data.xml" xpointer="EIO"/>
|
|
</variablelist>
|
|
</refsect2>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Notes</title>
|
|
|
|
<xi:include href="threads-aware.xml" xpointer="strict"/>
|
|
|
|
<xi:include href="libsystemd-pkgconfig.xml" xpointer="pkgconfig-text"/>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Examples</title>
|
|
|
|
<para>Use the <function>SD_JOURNAL_FOREACH_UNIQUE()</function> macro to iterate through all values a field
|
|
of the journal can take (and which can be accessed on the given architecture and are not compressed with
|
|
an unsupported mechanism). The following example lists all unit names referenced in the journal:</para>
|
|
|
|
<programlisting><xi:include href="journal-iterate-unique.c" parse="text" /></programlisting>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>History</title>
|
|
<para><function>sd_journal_query_unique()</function>,
|
|
<function>sd_journal_enumerate_unique()</function>,
|
|
<function>sd_journal_restart_unique()</function>, and
|
|
<function>SD_JOURNAL_FOREACH_UNIQUE()</function> were added in version 195.</para>
|
|
<para><function>sd_journal_enumerate_available_unique()</function> was added in version 246.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>See Also</title>
|
|
|
|
<para>
|
|
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</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_enumerate_fields</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>sd_journal_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
|
</para>
|
|
</refsect1>
|
|
|
|
</refentry>
|