Shell Programming and Scripting

sed 's/\("[^,]*\),\([^,]*"\)/\1\2/g' input.txt

$ cat input.txt
rohan,rahul,kunal,"sw,ati"
rohan,rahul,"k,un,al",swati
rohan,"rah,ul",kunal,swati
"ro,han",rahul,kunal,swati
rohan,rahul,kunal,swati

$ ./script.pl
rohan,rahul,kunal,swati
rohan,rahul,kunal,swati
rohan,rahul,kunal,swati
rohan,rahul,kunal,swati
rohan,rahul,kunal,swati

#!/usr/bin/perl -w
use warnings;
use strict;

open( FH, "input.txt" ) || die "Can't open the input file: $!";

while (<FH>) {
    chomp;
    m/"(\w+[,\w+]+)"/g;
    my $line = $1;
    $line =~ s/,//g;
    s/"(\w+[,\w+]+)"/$line/g;
    print $_. "\n";
}

close(FH);
exit 0;

#!/bin/sed -f
	h
 	s/\("[^",]*\),\?\([^"]*"\)/\1\2/g
	x;G;:c;tc
	s/^\(.*\)\n\1$/\1/
	t
	D

sed '
{
:a
sed 's/\("[^,]*\),\([^,]*"\)/\1\2/g' 
ta
}
'  input.txt