Linux

hi,

i have 2 dates in the form: '20080315120030' and '20080310140030'. i.e. YYYYMMDDHHMMSS.

i need a way of getting the difference between them using shell script.

any thoughts?

note i only have the following date utility:

usage: date [-u] mmddHHMM[[cc]yy][.SS]
date [-u] [+format]
date -a [-]sss[.fff]

at present i have this:

for file in `find ${my_dir}/ -name "*_statsfile_??????????????.gz" -print`
do
ONEDAY=86400
NOW=$(date -u +%Y%m%d%H%M%S)

FILEDATE=`echo $file | sed -e 's/^.*_stats_//g' -e 's/\.gz$//g'`

((DIFF=$NOW - $FILEDATE))
CALC_DIFF=$(($DIFF / $ONEDAY))

echo "[$file], Current Time: $NOW. File Time: $FILEDATE. Difference: $CALC_DIFF."
done


both dates need to be in UTC. Is there a way to make them BOTH UTC. the date 'NOW' is UTC but the 'FILEDATE' isnt.

It's possible but it would help if you could say which time zone the second one is.

The standard solution would be to convert them both to a canonical format (maybe epoch, that is, seconds since Jan 1 1970) and then the problem is just how to format the result back as a human-readable time expression. In what form would you like the output?

I would use Perl or Python because they come with handy libraries which can do the grunt work for you.

at the moment the first date, NOW is using date -u (UTC) and the file names will also be UTC. At present i have created dummy files with made up time stamps.

i basically want to delete files over 3 days old in a directory using the current date as a marker...i cant use -mtime as a person may modify the file and the modified time will not be the same as the filename. So therefore i am using the filename as the second time stamp. if you follow me?

im only after the number of days between the 2 dates.

If you have control over the file names then simply compare the date stamp in the file's name with the output of

Code:

date -d "3 days ago" -u +%Y%m%d%H%M%S

thats where the problem is, i get the following error:

date: illegal option -- d
usage: date [-u] mmddHHMM[[cc]yy][.SS]
date [-u] [+format]
date -a [-]sss[.fff]