use strict;
use warnings;

die "usage: perl $0 file.name \n" unless @ARGV;;
my $filename_in  = "topol1.top";

print "processing '$filename_in' \n";

my $filename_out = "$filename_in.new";

open my $fh_in,  '<', $filename_in  or die "opening '$filename_in': $!";
open my $fh_out, '>', $filename_out or die "opening '$filename_out': $!";

while (<$fh_in>) {
  s{ (SOL) [^\n]* }{$1 $sol1}xmsg;
  print $fh_out $_ or die "writing '$filename_out': $!";
  }

close $fh_in  or die "closing '$filename_in': $!";
close $fh_out or die "closing '$filename_out': $!";

rename $filename_in, "$filename_in.bak" or die "renaming '$filename_in': $!";
rename $filename_out, $filename_in      or die "renaming '$filename_out': $!";