Shell Programming and Scripting

Hi radoulov,

Command that you suggested is working.

For my knowledge can you please elaborate how it works.

Thanks radoulov,
Amit

Yes, of course.

Code:

{ 
  _[$1] = _[$1] ? _[$1] FS $2 : NR == FNR ? $2 : FS $2
  if ($1 > m) m = $1 
  }

Populate an associative array (_), key-value pair is $1 - $2.
While doing so, if the key already exists, just add the new value
to the previous one, the _[$1] ? _[$1] FS $2 : $2 part. The last
$2 is an expression: NR == FNR ? $2 : FS $2 - if the current value
is from the first file (while the expression NR == FNR returns true),
return just $2, otherwise - return FS $2 (the records with first column 5 and 6).

Code:

if ($1 > m) m = $1

This searches the upper limit of your $1 values (in your case it's a numeric column).

Code:

END { 
  for (i=1; i<=m; i++) 
    print i, _[i] 
    }

After the entire input has been read, print the key - value pairs in the _ array in numeric order.

Thanks for the explanation radoulov.

Amit

join(1) is a relational database operator. If your version of join conforms to
POSIX.1:2004 or SUSv3 i.e.supports the -0 0 outer join operation, the
following

Code:

join -t, -a 1 -a 2 -o 0,1.2,2.2 file1 file2

gives the expected output

Useful,
thanks!