Question

I’m trying to work on a logfile, and I need to be able to specify the range of dates. So far (before any processing), I’m converting a date/time string to timestamp using date --date "monday" +%s.

Now, I want to be able to iterate over each line in a file, but check if the date (in a human readable format) is within the allowed range. To do this, I’d like to do something like the following:

echo `awk '{if(`date --date "$3 $4 $5 $6 $7" +%s` > $START && `date --date "" +%s` <= $END){/*processing code here*/}}' myfile`

I don’t even know if thats possible… I’ve tried a lot of variations, plus I couldn’t find anything understandable/usable online.

Thanks

Update:

Example of myfile is as follows. Its logging IPs and access times:

123.80.114.20      Sun May 01 11:52:28 GMT 2011
144.124.67.139     Sun May 01 16:11:31 GMT 2011
178.221.138.12     Mon May 02 08:59:23 GMT 2011

Answer 1

Given what you have to do, its really not that hard AND it is much more efficient to do your date processing by converting to strings and comparing.

Here’s a partial solution that uses associative arrays to convert the month value to a number. Then you rely on the %02d format specifier to ensure 2 digits. You can reformat the dateTime value with ‘.’, etc or leave the colons in the hr:min:sec if you really need the human readability.

The YYYYMMDD format is a big help in these sort of problems, as LT, GT, EQ all work without any further formatting.

echo "178.221.138.12     Mon May 02 08:59:23 GMT 2011" \
| awk 'BEGIN {
mons["Jan"]=1 ; mons["Feb"]=2; mons["Mar"]=3
mons["Apr"]=4 ; mons["May"]=5; mons["Jun"]=6
mons["Jul"]=7 ; mons["Aug"]=8; mons["Sep"]=9
mons["Oct"]=10 ; mons["Nov"]=11; mons["Dec"]=12
}
{ 
   # 178.221.138.12     Mon May 02 08:59:23 GMT 2011
   printf("dateTime=%04d%02d%02d%02d%02d%02d\n", 
       $NF, mons[$3], $4, substr($5,1,2), substr($5,4,2), substr($5,7,2) )
} ' -v StartTime=20110105235959

The -v StartTime is ilustrative of how to pass in (and the matching format) your starTime value.

I hope this helps.