How old is that file?

APLawrence.com - Resources for Unix and Linux Systems, Bloggers and the self-employed

How old is that file?

I've removed advertising from most of this site and will eventually clean up the few pages where it remains.

While not terribly expensive to maintain, this does cost me something. If I don't get enough donations to cover that expense, I will be shutting the site down in early 2020.

If you found something useful today, please consider a small donation.

Some material is very old and may be incorrect today

© November 2004 Tony Lawrence

(Traditional format)

Tue Nov 2 16:16:41 2004 How old is that file?
Posted by Tony Lawrence
Search Keys: shell

Sometimes you want to know the age of a file. Perl has a "-M" test that gives you age in days, but this customer needed it in minutes. That's easy:

#!/usr/bin/perl
# howold.pl
$file=shift @ARGV;
@stat=stat $file;
$now=time();
$mtime=sprintf("%d",($now -$stat[10])/60);
# That's inode change time, stat[9] would be modification, and 8 is access
print "$mtime\n";

You'd use this in a script like this:

OLD=`howold.pl myfile`
if [ "$OLD" -gt 20 ]
then
  echo "older than 20 minutes"
else
  echo "Younger"
fi

You could put the whole script on one line:

printf("%d\n",(time() - (stat(@ARGV[0]))[10] )/60);

but that's much harder to follow and a lot easier to screw up.

If you found something useful today, please consider a small donation.