I am sorry to confuse you, ok here i go again: There is an existing script (Lets call it ThirdPartyScript and i cannot do any modifications to it) which performs some processing and displays output on the STDOUT and at the end it asks for options. For example, when you provide an option "i" it means include flag and you can specify any search string. It then retrieves the results matching that search string from its database and after displaying those results it again wait for next action with the following prompt:

Select option:
[download]

Now, either you can provide next option as i (to include other search string or "d" to delete the listed results etc or "X" to quit script. Now, i am writing a perl script with the intention to run above thirdpartyscript with a specific search string from this perl code and write the result of this run to a unix file. Then again my perl code will email this output file to the interested parties. My perl code works fine when i run that for any other command (e.g. ls), but when i run that for the above third party script, it never completes execution and the output file never populated. So, i thought may be it is because the thirdpartyscript do not exit execution until an "x" is specified as explained above. Please let me know if it helps. Thanks