I have a task where I need to code a shell script to extract a 10 min range (10 min from now until now) extract of a log file.

I taught I could simply use a command that would say something like Start=date - 10 min but I didn't find anything. Looks like the only solution would have to code a small script that would extract the time, strip the values, sub 10 min, check for month and year crossover and convert back into a date string.

Idealy, if there was a command to extract all records from start (chronologicaly reveresed) up until matching record= 10 min back, that would be great. I seriously dought there would be such a thing.

Any suggestions ? I'm a Unix script beginner.

Post some sample data.

sample file to have 10 min extracted. It is the result of an fgrep done on several log files on specific keywords :

/export/home/..../filea.log:2005-11-14 12:01:03,999 xxxxxxxxxxxxxxx
/export/home/..../filea.log:2005-11-14 12:01:02,123 xxxxxxxxxxxxxxx
/export/home/..../filea.log:2005-11-14 12:01:01,345 xxxxxxxxxxxxxxx
...

The logs are live and therefore always updated.

Once I have the date-10min value, wouldn't it be possible to somehow get the line# of where the 10 min matches and have a command that only gets from the start up to that line# ?

With only 10 minutes to look for, you could put all 10 timestamps in one grep statement. To reverse the lines, prepend line numbers, sort in reverse order on the line numbers, and remove the line numbers. This script uses datacalc which you can find on this site.

#! /usr/bin/ksh

date "+%Y %m %d %H %M" | read year month day hour minute
pattern=""
count=10
while((count)) ; do
        now="${year}-${month}-${day} ${hour}:${minute}"
        ((count=count-1))
        if ((minute)) ; then
                ((minute=minute-1))
        else
                minute=59
                if ((hour)) ; then
                        ((hour=hour-1))
                else
                        hour=23
                        datecalc -a $year $month $day - 1 | read year month day
                fi
        fi
        [[ -n $pattern ]] && pattern="${pattern}|"
        pattern="${pattern}${now}"
done
pattern=$(echo $pattern | tr "|" "\n")

grep -F "$pattern" | nl -ba | sort -nr | cut -f2-
exit 0