Polling continously for presence of a file

Hi,
My os is sun solaris 5.10 and Korn shell scripting.

I have a file name like CCNA_EARLY_SWP.w062309
where 062309 is date in mmddyy .This is the value date of the file.(will
I need to check continously from 5.00 - 7.00 am daily for this file .
If the file has not come at 5 am or 7am ,I need tor aise alert message.
If the file has not come at 7am , i need to exit from script with error return code.
Apart from this, I do not want to poll continously , if the time is not between 5.00 and 7.00 am , but only check for presence of file,if present do next step otherwise exit with error code.

Can anyone give some good example to proceed

man cron

you need to setup a cron job, to know more, read here

I'm using ETL to call unix script.
How can I achieve the requirement in unix script itself

before checking for file get the time stamp if it is not in your range --sleep for some time and then wake up
If your bail out time reach and still the file not present --Sent a mail and Exit from the script

You can consider using scheduler -like Autosys which is equiped with file watcher functionality