pick up files based on dates in ksh script - shell

Question

I have this list of files . Now I will have to pick the latest file based on some condition
3679 Jul 21 23:59 belk_rpo_error_**po9324892**_07212014.log
0 Jul 22 23:59 belk_rpo_error_**po9324892**_07222014.log
3679 Jul 23 23:59 belk_rpo_error_**po9324892**_07232014.log
22 Jul 22 06:30 belk_rpo_error_**po9324267**_07012014.log
0 Jul 20 05:50 belk_rpo_error_**po9999992**_07202014.log
411 Jul 21 06:30 belk_rpo_error_**po9999992**_07212014.log
742 Jul 21 07:30 belk_rpo_error_**po9999991**_07212014.log
0 Jul 23 2014 belk_rpo_error_**po9999991**_07232014.log
For a PATRICULAR Order_No(Marked with ** **)
If the latest file is 0 kB then we will discard it (rest of the files with same Order_no as well)
if the latest file is non Zero then I will take it.(Only the latest one)
Then append the contents in a txt file .
My expected output would be ::
411 Jul 21 06:30 belk_rpo_error_**po9999992**_07212014.log
3679 Jul 23 23:59 belk_rpo_error_**po9324892**_07232014.log
22 Jul 22 06:30 belk_rpo_error_**po9324267**_07012014.log
I am at my wits end here. I cant seem to figure out how to compare dates in Unix. Any help is very appreciated.

Answer 1

You can try something like:
touch test.txt
for var in ` find . ! -empty -exec ls -r {} \;`
do
cat $var>>test.txt
done

Answer 2

untested
use stat to emit date (epoch time), size and filename.
use awk to filter out zero-length files and extract order number.
sort by order number and date
awk to pick up the last filename for each order number
stat -c $'%Y\t%s\t%n' *.log |
awk -F'\t' -v OFS='\t' '
$2 > 0 {
split($3, a, /_/)
print a[4], $1, $3
}' |
sort -t $'\t' -k1,1 -k2,2n |
awk -F'\t' '
NR > 1 && $1 != prev_order {print filename}
{filename = $3; prev_order = $1}
END {print filename}
'
The sort command might be wrong: In order to group by order number, you might need to sort first by file time then by order number.
If I understand your question, the resulting files need to be concatenated and appended to a file. If the above pipeline is working OK, then pipe into | xargs cat >> something.log