shell script to maintain the log files

[thanigai]

hi all
can anyboby help me to make shell scripts to do
1.Maintanence of alert log files-to have only last two months of log files
2.maintanence of listner.log and sqlnet.log files to have only two weeks of logs.
meaning Scripts to delete log files everymonth/2weeks.
I badly need those immediatly to implement in our office.(Right now we are manually doing)
Please help me.
Thanks in Advance.