How old is that file?

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.

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