OK, again:
There only is "something strange" about s and t, because you tell getopt to read values for these switches, calling it getopt('st'). The parameter for getopt doesn't contain "allowed" switches, it contains switches that expect an argument.
If you don't need values for these switches (which seems to be the case) just don't name them in the first parameter to getopt. Getopt will still, when it stumbles upon that switch on the command line, define the hash entry for the given letter and give it a value of 1.
