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<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>
+ <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>
~ianmdlvl / elogind.git / blobdiff