Windows版本：
@echo off
setlocal
set REPOS=%1
set TXN=%2
rem check that logmessage contains at least 10 characters
svnlook log "%REPOS%" -t "%TXN%" | findstr ".........." > nul
if %errorlevel% gtr 0 goto err
exit 0
:err
echo Empty log message not allowed. Commit aborted! 1>&2
exit 1
Linux版本：
#!/bin/sh
REPOS="$1"
TXN="$2"
SVNLOOK=/usr/bin/svnlook
# check that logmessage contains at least 10 alphanumeric characters
LOGMSG=`$SVNLOOK log -t "$TXN" "$REPOS" | grep "[a-zA-Z0-9]" | wc -c`
if [ "$LOGMSG" -lt 10 ];
then
echo -e "\nEmpty log message not allowed. Commit aborted!" 1>&2
exit 1
fi
关于钩子如何使用，可以看看这个章节
http://www.subversion.org.cn/svnbook/1.1/svn-ch-5-sect-2.html#svn-ch-5-sect-2.1
