Try This one
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Once again I dun have any *NIX box with me. So why Just giving one logic by which you will get your answer.
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#!/bin/bash
## List all the files which one accessed since last 1 min #####
for file_dir in `find <parent-dir> -atime -1`
do
### Find out the PID for that files which one been accessed
pid=`fuser -f $file_dir`
### Find out the owner/user name for that Process
### Replace the $access_user_filed with the filed no from the ps -ef
### command
user=`ps -ef | grep $pid | awk { print $access_user_filed }`
echo " $file_dir access by the $user " >> File_Access_List "
mail -s " File Access List "
user@yourdomain.com < File_Access_List
done