Doc: Document log rotation feature

diff --git a/doc/bird.sgml b/doc/bird.sgml
index c0999d2db29b81ccbe5690112f4b3e4f6944636f..8dc872e70b2c6cc35dbf4044bea5c35788f54b67 100644 (file)
--- a/doc/bird.sgml
+++ b/doc/bird.sgml
@@ -471,17 +471,25 @@ ipv6 table
 include "tablename.conf";;
 </code>
 
-       <tag><label id="opt-log">log "<m/filename/"|syslog [name <m/name/]|stderr all|{ <m/list of classes/ }</tag>
-       Set logging of messages having the given class (either <cf/all/ or
-       <cf/{ error|trace [, <m/.../] }/ etc.) into selected destination (a file specified
-       as a filename string, syslog with optional name argument, or the stderr
-       output). Classes are:
+       <tag><label id="opt-log">log "<m/filename/" [<m/limit/ "<m/backup/"] | syslog [name <m/name/] | stderr all|{ <m/list of classes/ }</tag>
+       Set logging of messages having the given class (either <cf/all/ or <cf>{
+       error|trace [, <m/.../] }</cf> etc.) into selected destination - a file
+       specified as a filename string (with optional log rotation information),
+       syslog (with optional name argument), or the stderr output.
+
+       Classes are:
        <cf/info/, <cf/warning/, <cf/error/ and <cf/fatal/ for messages about local problems,
        <cf/debug/ for debugging messages,
        <cf/trace/ when you want to know what happens in the network,
        <cf/remote/ for messages about misbehavior of remote machines,
        <cf/auth/ about authentication failures,
        <cf/bug/ for internal BIRD bugs.
+
+       Logging directly to file supports basic log rotation -- there is an
+       optional log file limit and a backup filename, when log file reaches the
+       limit, the current log file is renamed to the backup filename and a new
+       log file is created.
+
        You may specify more than one <cf/log/ line to establish logging to
        multiple destinations. Default: log everything to the system log, or
        to the debug output if debugging is enabled by <cf/-d//<cf/-D/