The below example is for moving (mv) files, same can be changes easily for rm, ls, cp etc. One has to make change in xargs paramaeter.
In LINUX:
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find /path_to_directory/ -name "*.rpt" -type f -mmin +15 | xargs -I {} mv {} /target_directory_path/
In Solaris:
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#! /usr/bin/sh
#### Create a reference file minute_test
touch /path_to_directory/minute_test
#### Make minute_test 15 minutes old
sleep 900
#### Move all .rpt files to some other directory which are older than reference file minute_test
find /path_to_directory/ -name "*.rpt" -type f -newer minute_test | xargs -I {} mv {} /target_directory_path/
#### Remove reference file
rm -f /path_to_directory/minute_test