Difference between cd - vs cd ~-

Yesterday I posted one of my old (16 years ago) blog entries on twitter, Backtracking with Bash which shows a cool trick you can use to go to the directory you were previously in using cd ~- for example:

$ cd /var
$ cd /etc
$ cd ~-
$ pwd
/var

Ryan Guill pointed out that cd - also works, so what is the difference between cd ~- and cd -?

$ cd /var
$ cd /etc
$ cd -
/var
$ pwd
/var

So what is the difference?

The biggest difference between cd ~- and cd - is that ~- can be used in any command because it is part of the shells tilde expansion. The - shortcut can only be used with the cd command.

So for example if your directory was previously /var/log/apache2 and you want to tail the access_log file in there you can just tail ~-/access_log

$ cd /var/log/apache2
$ cd /etc
$ tail ~-/access_log
It Works...
$ tail -/access_log
tail: illegal option -- /

The second difference is that cd - will print the directory it changed to out to standard output, and cd ~- just changes directories without printing anything.