File date vs Current date

Shell Programming and Scripting
1

I am a newbie in shell scripting, hope you can advice how can I compare the date/time of file extracted from 'll' and current system date/time.

I have done the following:

ll -rt > $FILE_AGE_LOG
FILE_DATETIME=`more $FILE_AGE_LOG | head -02 | cut -c 45-57`

It returns 'May 4 19:11'.

If I want to put in a condition to check if the file is more than 15 minutes old, something like the following.

if [ $FILE_DATETIME < (`date`-15) ]

Please kindly advice how can I do that?
Thanks.

2

Trexlim,
A true date calculation can be very involved as you have to consider leap years.
One way to solve your problem is:
1) One time only, create a "15_minutes_file".
2) Create a cron job that runs every 15 minutes.
2.a) Test if the file is older than 15_minutes_file -- "if file -ot 15_minutes_file"
2.a.I) Meets your criteria.
2.b) Update (touch) the "15_minutes_file" file with the current date.
See if this works for you.

3

try something like this:

#!/bin/ksh
# tdiff.sh 


tdiff()
{
perl -e '
   ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
   $atime,$mtime,$ctime,$blksize,$blocks) = stat("$ARGV[0]");
   $difference = time - $mtime;
   print $difference;
   ' "$1"
}

secs=$(tdiff "$1")
minutes=$secs/60
if [[ $minutes -le 15 ]] ; then
    echo "$1 is 15 minutes old or less"
else
    echo "$1 is older than 15 minutes"    
fi
4

You could after touching the 'timestamp' file, do
'ls -ltr' and see what files are listed after the datestamp file.
Note that the granularity of the list may only be to the nearest minute.

5