$_ =  "foo        bar        baz     ";
my $catdesc = " extra ";

print join(",", ("", map /^\s*(.*\S)/, unpack("a10 a10 a10", $_), $catdesc)[0,0,-1,0,0,3,0,0,1,2,0] );

# output: ",,extra,,,baz,,,foo,bar,"