Thanks for the suggestionsSorry for not formatting the question properly and not listing my code.

The code works but I am facing another problem.

I am sorting a file that it more than 400MB size and using multiple keys. While executing, the sort fails with core dump and sometimes illegal instruction message.

I did some investigation and found out that it is due to insufficeint memory.

I am running it on AIX server and when I did ulimit -a it gave memory as 65536 bytes. I have unlimited file size permission. I reduced the size of the input file to about 60 K and the sort worked. I have checked and I can't use malloc() or reset it to be used during runtime.

   use strict;
   use Encode qw(encode decode);
   ### Define the sort key here ###
   # Sorts in ascending order.
    sub key1  { ( substr( $a, 3, 17 )) cmp ( substr( $b, 3, 17 )); }
     # Sorts  descending order.
    sub key2  { ( substr( $b, 20, 2 )) cmp ( substr( $a, 20, 2 )); }
    #
    ### Sort processing starts ###
    my @infile = <>; # Reads file
    ### Multiple sort keys can be defined and sorted in the order of t
+he key
    my @sorted = map { decode('cp1047', $_) } sort { key1 || key2 } (m
+ap
    { encode('cp1047', $_) } @infile);
    print @sorted;
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Do a GRT through /bin/sort.

# ...
use IPC::Open2 'open2';
my( $chaos, $sorted );
my $pid= open2( $sorted, $chaos, 'sort' );
while(  <>  ) {
    my $ascii= encode( 'cp1047', $_ );
    print $chaos substr($ascii,3,17), substr($ascii,20,2), $_;
}
close $chaos;
while(  <$sorted>  ) {
    print substr( $_, 19 );
}
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or thereabouts. It looks like your EBCDIC file is using ASCII newlines, which simplifies things.

- tye