Shell Programming and Scripting

I have 2 files - fileA and fileB
I need to match the first field of the 2 files then output some of the fields from fileA on the same line as certain fields from fileB.
There will be instances where fileB does not have a match for first field in fileA
Thanks in advance

if you could elaborate on what exactly needed to be done with the sample input and the expected output, someone here could probably have helped you.

As a starting point I would look into awk's associative arrays.

You also might want to look at the "join" command. It has a man page.

Apologies vgersh99 I'll try to elaborate.
fileA would look something lke this
500,22,1001,16,22,0,4
501,23,2004,16,26,1,9
502,44,1003,18,0,0,10
503,43,1000,22,1,14,15
504,40,1006,20,0,22,22
505,32,1009,21,11,32,88
fileB might look like this:
500,Florence,30,477
501,Zebedee,28,505
503,Dougal,80,609
504,Brian,70,300

As you can see, 502 and 505 are missing from fileB and therefore the match would fail. There wouldn't be an instance where fileB contained a value in 1st fields which doesn't appear in fileA.
The output should contain the first 4 fields from fileA together with fields 3 and 4 from fileB on the same line. Where there is no match in fileB these values should contain zero.
EG
500,22,1001,16,30,477
501,23,2004,16,28,505
502,44,1003,18,0,0
503,43,1000,22,80,609
504,40,1006,20,70,300
505,32,1009,21,0,0

Hope this makes more sense - thanks again

nawk -f mud.awk fileB fileA

here's mud.awk:

Code:

BEGIN {
  FS=OFS=","
  defValues="0" OFS "0"
}

FNR == NR {
  arr[$1] = $3 OFS $4
  next
}

{
   NF=5
   $5 = ( $1 in arr ) ? arr[$1] : defValues
   print
}

Thanks vgersh99 - That works fine. One further question - is there a maximum number of indices which can be applied to an array - my real-world application will work on files which may have thousands ( or 10s of thousands) of records.
Thanks Again

this is limited by the physical memory [for the well-behaved awk's].