I've looked for a while, and it seems that there is no easy way to do
this, not even in bash, and worse with /bin/sh. So this is kind of
resorting to a simple parsing of the input, and using `eval' if it
starts with a tilde. Note the hack of not doing that when there is a
space, otherwise the `eval' thing will silently ignore it.
This hack means that it's easy to get into a mess if quotes are used
after a tilde, but that was already the case with the use of `eval' to
handle environment variables. It's not a real security issue, however,
since we're talking about a user who can just run any command anyway.
Also including a test file for the expansion functionality. If anyone
wants to improve this code, making the tests pass would reveal the
tricky issues.
[FWIW, I've asked on the #bash channel, and the only serious suggestion
was getting the paths as command-line arguments. This will, however,
defeat the point of being newbie friendly...]
Closes PR 12893.
It's now simpler, shorter, and better. Some of the text is revised,
accepts environment variables when asked for the path, some additional
fixes in misc places.
