It would seem that s and t are indeed strange in Getopt::Std.
I disagree. There is no evidence which supports the claim that s and t are strange in any way. I tried using a and b instead of s and t in my example, and the behavior is the same. Give it a try.
I did think that, if one expected to use -t <value> on the command line then the expected syntax for getopt would be getopt('st:',\%opt); with the : indicating a required value for the argument.
The getopts function (notice the "s" on the end) uses the ":" syntax, not the getopt function. So, it seems that, contrary to the docs, getopts requires you to supply a <value> with each switch.

In reply to Re^3: Detecting an undefined hash key by toolic
in thread Detecting an undefined hash key by LesleyB

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