while ( (print "Enter Command: "), 
        (my $line = <STDIN>) !~ /^\s*q(uit)?\s*$/i  
      )
{
   next   if $line =~ /^\s*$/;        #skip new lines
   next   if $line =~/^\s*skip/i;     #skip is a no op command
   insert if $line =~/^\s*insert/i;   #do insert command
   delete if $line =~/^\s*delete/i;   #do delete command
   #...etc..
}
sub insert()
{...}
sub delete()
{...}