bin/57483 reports that tail(1) doesn't correctly handle old style options in all cases. The current approach taken by tail is to massage the command line to convert old style options into the new style options and then use getopt to parse only the new style. Unfortunately the code that does the conversion is a bit naive, so it doesn't notice that in -fn +20 the "+20" is not a standalone old style option but an argument to the new style -n hidden/fused into "-fn".
I sketched a prototype to parse both new and old style options together but the comments about incompatibilities with historic behavior give me pause. Cf. https://anonhg.netbsd.org/src/file/tip/usr.bin/tail/tail.c#l76 The man page seems to be completely silent about the old style options. What exactly are we aiming for here? Do we want to support postfix options in something like old style +<n>qF ? -uwe
