How can I translate tildes in a filename?

    Perl doesn't expand tildes -- the shell (ok, some shells) do.
    The classic request is to be able to do something like:

        open(FILE, "~/dir1/file1");
        open(FILE, "~tchrist/dir1/file1");

    which doesn't work.  (And you don't know it, because you 
    did a system call without an "|| die" clause! :-)

    If you *know* you're on a system with the csh, and you *know*
    that Larry hasn't internalized file globbing, then you could
    get away with 

        $filename = <~tchrist/dir1/file1>;

    but that's pretty iffy.

    A better way is to do the translation yourself, as in:

        $filename =~ s#^~(\w+)(/.*)?$#(getpwnam($1))[7].$2#e;

    More robust and efficient versions that checked for error conditions,
    handed simple ~/blah notation, and cached lookups are all reasonable
    enhancements.