Merge pull request #1848 from poettering/journal-sync

add journalctl --sync command and other stuff

2 files changed, 44 insertions, 9 deletions

diff --git a/man/journalctl.xml b/man/journalctl.xml
index a3192539dc..b57afb6ebf 100644
--- a/man/journalctl.xml
+++ b/man/journalctl.xml
@@ -773,21 +773,41 @@
       </varlistentry>
 
       <varlistentry>
+        <term><option>--sync</option></term>
+
+        <listitem><para>Asks the journal daemon to write all yet
+        unwritten journal data to the backing file system and
+        synchronize all journals. This call does not return until the
+        synchronization operation is complete. This command guarantees
+        that any log messages written before its invocation are safely
+        stored on disk at the time it returns.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
         <term><option>--flush</option></term>
 
         <listitem><para>Asks the journal daemon to flush any log data
         stored in <filename>/run/log/journal</filename> into
-        <filename>/var/log/journal</filename>, if persistent storage is
-        enabled. This call does not return until the operation is
-        complete.</para></listitem>
+        <filename>/var/log/journal</filename>, if persistent storage
+        is enabled. This call does not return until the operation is
+        complete. Note that this call is idempotent: the data is only
+        flushed from <filename>/run/log/journal</filename> into
+        <filename>/var/log/journal</filename> once during system
+        runtime, and this command exits cleanly without executing any
+        operation if this has already has happened. This command
+        effectively guarantees that all data is flushed to
+        <filename>/var/log/journal</filename> at the time it
+        returns.</para></listitem>
       </varlistentry>
 
       <varlistentry>
         <term><option>--rotate</option></term>
 
-        <listitem><para>Asks the journal daemon to rotate journal files.
-        </para></listitem>
+        <listitem><para>Asks the journal daemon to rotate journal
+        files. This call does not return until the rotation operation
+        is complete.</para></listitem>
       </varlistentry>
+
       <xi:include href="standard-options.xml" xpointer="help" />
       <xi:include href="standard-options.xml" xpointer="version" />
       <xi:include href="standard-options.xml" xpointer="no-pager" />
diff --git a/man/systemd-journald.service.xml b/man/systemd-journald.service.xml
index 21fd684b8b..f1054b03bb 100644
--- a/man/systemd-journald.service.xml
+++ b/man/systemd-journald.service.xml
@@ -131,15 +131,30 @@ systemd-tmpfiles --create --prefix /var/log/journal</programlisting>
         this is enabled). This must be used after
         <filename>/var/</filename> is mounted, as otherwise log data
         from <filename>/run</filename> is never flushed to
-        <filename>/var</filename> regardless of the
-        configuration.</para></listitem>
+        <filename>/var</filename> regardless of the configuration. The
+        <command>journalctl --flush</command> command uses this signal
+        to request flushing of the journal files, and then waits for
+        the operation to complete. See
+        <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+        for details.</para></listitem>
       </varlistentry>
 
       <varlistentry>
         <term>SIGUSR2</term>
 
         <listitem><para>Request immediate rotation of the journal
-        files.</para></listitem>
+        files. The <command>journalctl --rotate</command> command uses
+        this signal to request journal file
+        rotation.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term>SIGRTMIN+1</term>
+
+        <listitem><para>Request that all unwritten log data is written
+        to disk. The <command>journalctl --sync</command> command uses
+        this signal to trigger journal synchronization, and then waits
+        for the operation to complete.</para></listitem>
       </varlistentry>
     </variablelist>
   </refsect1>
@@ -261,7 +276,7 @@ systemd-tmpfiles --create --prefix /var/log/journal</programlisting>
       <citerefentry><refentrytitle>systemd-coredump</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
       <citerefentry project='die-net'><refentrytitle>setfacl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>4</manvolnum></citerefentry>,
-      <command>pydoc systemd.journal</command>.
+      <command>pydoc systemd.journal</command>
     </para>
   </refsect1>