Do you know of any recipes that call for tildes?

7.3. Expanding Tildes in Filenames

Problem

You want to open filenames like ~username/blah, but open doesn't interpret the tilde to mean a home directory.

Solution

Expand the filename manually with a substitution:

$filename =~ s{ ^ ~ ( [^/]* ) }
                      { $1
                                ? (getpwnam($1))[7]
                                : ( $ENV{HOME} || $ENV{LOGDIR}
                                       || (getpwuid($>))[7]
                                    )
}ex;

Discussion

The uses of tilde that we want to catch are:

      ~user
      ~user/blah
      ~
      ~/blah

If no name follows the ~, the current user's home directory is used.

This substitution uses /e to evaluate the replacement as Perl code. If a username follows the tilde, it's stored in $1, which getpwnam uses to extract the user's home directory out of the return list. This directory becomes the replacement string. If the tilde was not followed by a username, substitute in either the current HOME environment variable or the LOGDIR one. If neither of those environment variables is valid, look up the effective user ID's home directory.