Hi I'm new to unix programming so struggling with something thats probably simple to many of you

I have data files of the format :

ID, date, value1, value2, blank

on each line either value1 or value2 will be zero. I need my output file to contain

ID, date, non-zero value

The input and output filenames need to be the same (extension can possibly be different). The ID is of variable length.

I've tried using cut and if to identify the non-zero field and have also played with summing value1 and value2 (if one is always zero then the result is correct). I've spent today trying to learn awk and have come up with a few wrong answers, can anybody help please

Thanks in anticipation

A quick solution would be this, but I fell awk would have been better

$ cat thefile.out
ID1,23-12-1983,32,12,
ID2,12-12-1982,,21,
ID3,14-06-2007,12,,
$ sed -e 's/,,/,/' -e 's/,$//' thefile.out > thefile.tmp
$ cat thefile.tmp
ID1,23-12-1983,32,12
ID2,12-12-1982,21
ID3,14-06-2007,12

I am haven't understood it wrong then this is the soln

cat filename:

ID1,23-12-1983,2,0,
ID2,12-12-1982,0,21,
ID3,14-06-2007,12,0,
ID4,14-09-2008,0,33,


[code :]

awk -F',' '{print $1","$2","($3+$4)};' filename

[code :]

That's great, thanks....as it happens I wasn't too far off!