Find the age of a file in Minutes

Shell Programming and Scripting
1

KSH:
Please lt me know how to find the age of a file in minutes(Based on last modified time).
ie, if the file was modified 15 Minutes ago, the output should be 15

2

Here is how I would do in ksh:
perl -e 'printf "%d\n" ,(time()-((stat(shift))[9]))/60;' file1.txt

Sorry, but sometimes ksh falls short and you need perl for an assist.