You could use stat():
if ( (time - (stat FILE)[10]) / (60*60*24) > 5 ) { ... }
Actually, as -M is "Script start time minus file
modification time, in days", you'd have to store the return value
of time() right at the beginning of the script, to get the exact
equivalent for ctime... though I suppose the difference would be negligible. (Update: actually (RTFM :) — use "perldoc -f -X" to get the docs for the filetests...) there even seems to be an option -C which does just that...)
Alternatively (Update2: and preferably — see kenneth/MidLifeXis's comments below), reset the modification time to what it was before, every time you make a modification...
