From: Bartosz Fenski <fenio@debian.org>
Subject: If running inside Emacs M-x shell, turn of colors by default

--- a/ipcalc
+++ b/ipcalc
@@ -708,7 +708,13 @@ sub getopts
    if (-t STDOUT) {
       $opt_color = 1;
    }
-   
+
+   # Under Emacs, do not use colors by default. The TERM is for older
+   # Emacs versions.
+   if ( !defined($ENV{'TERM'}) or $ENV{'TERM'} =~ /dumb/i  or  $ENV{'INSIDE_EMACS'} ) {
+       $opt_color = 0;
+   }
+
    while (has_opts()) {
      $arg = shift @ARGV;
      if ($arg =~ /^--(.+)/) {
@@ -781,6 +787,9 @@ sub getopts
         elsif    ($opt eq 'help') {
 	   $opt_help = 1;
 	}
+	elsif ($opt eq 'c' || $opt eq 'color') {
+	   $opt_color = 1;
+	}
 	elsif ($opt eq 'n' || $opt eq 'nocolor') {
 	   $opt_color = 0;
 	}
@@ -1047,6 +1056,7 @@ can design sub- and supernetworks. It is also intended to be a teaching tool
 and presents the results as easy-to-understand binary values. 
 
  -n --nocolor  Don't display ANSI color codes.
+ -c --color    Display ANSI color codes (default).
  -b --nobinary Suppress the bitwise output.
  -c --class    Just print bit-count-mask of given address.
  -h --html     Display results as HTML (not finished in this version).
--