`$SHELL` variable is a terrible way of detecting the current shell
because it's not even supposed to reflect the current shell; it's meant
for keeping the value of the default shell for programs to start.
If an explicit `<shell>` argument wasn't passed to `rbenv init`, it
tries to detect the shell by getting the name of its parent process. If
this fails, it falls back on the value of `$SHELL` as before.
Furthermore, `rbenv init` will set the RBENV_SHELL variable in the
current shell to the value of the detected shell so that `sh-shell` and
`sh-rehash` commands don't have to repeat the detection.
If `rbenv init -` outputs `.` in place of `source` and that gets eval'd
by the desktop manager via `~/.profile`, it chokes and prevents the user
from logging in.
Fixes#457
Enables shelling out from a ruby process started with rbenv to a ruby
process with a different RBENV_VERSION. Fixes#121
This removes the workaround created for #15 and solves `ruby -S` support
by setting RUBYPATH. PATH is never changed.
To illustrate how RUBYPATH changes in various configurations:
PATH=~/bin:~/.rbenv/shims:/usr/bin:/bin
RBENV_VERSION=1.8 ruby -S rake
#=> executes ~/.rbenv/versions/1.8/bin/rake
#=> RUBYPATH=~/bin:~/.rbenv/versions/1.8/bin:/usr/bin:/bin
RBENV_VERSION=2.0 ruby -S rake
#=> executes ~/.rbenv/versions/2.0/bin/rake
#=> RUBYPATH=~/bin:~/.rbenv/versions/2.0/bin:/usr/bin:/bin
RBENV_VERSION=system ruby -S rake
#=> executes /usr/bin/rake
#=> RUBYPATH=~/bin:/rbenv_shims_were_here:/usr/bin:/bin
RBENV_VERSION=1.8 ruby -S rake
#=> executes ~/.rbenv/versions/1.8/bin/rake
#=> RUBYPATH=~/bin:~/.rbenv/versions/1.8/bin:/usr/bin:/bin
