implements purge algorithm for one slave; see: http://dev.mysql.com/doc/refman/5.0/en/show-binary-logs.html

purge_mysql_bin_logs.sh

#!/bin/sh


# implements purge algorithm for one slave
# see: http://dev.mysql.com/doc/refman/5.0/en/show-binary-logs.html
master=host1
slave=host2

username=user
password=pass


date 

slave_reading=$(mysql -u$username -p$password -h$slave -e'SHOW SLAVE STATUS\G'|grep ' Master_Log_File'|awk -F: '{print $2}')
all_master_logs=$(mysql -u$username -p$password -h$master -e'SHOW BINARY LOGS;')
master_n=$(echo $slave_reading | awk -F. '{print $2}')

echo "slave is reading $slave_reading"

upto=
for log in $all_master_logs; do
  l=$(echo $log | grep mysql-bin)
  if [ $l ]; then
    n=$(echo $log | awk -F. '{print $2}')
    if [ $n -lt $master_n ]; then
      echo "$log will be purged"
      upto=$log
    #else
    #  echo "$log >= $slave_reading, let's keep it . . ."
    fi
  fi
done

if [ $upto ]; then
  cmd="PURGE BINARY LOGS TO '$upto'"
  echo "$cmd"
  mysql -u$username -p$password -h$master -e "$cmd"
else
  echo "Nothing to purge"
fi

date