[ Thanks to Chris7mas for this link.
]
“cd – is the same as cd $OLDPWD, where the $OLDPWD
variable holds the previous working directory. You can also alias
this to something like:alias back='cd -' # or alias back='cd $OLDPWD'“If you’ve just opened a new Bash session or sourced .bashrc,
the $OLDPWD variable will be unset. Also, follow this discussion on
reddit which is a great resource on this matter.2. Make copies of files easier
This one is especially useful for creating backup files, but not
only. To fasten up rename commands like mv file1 file1bak you can
use something like:”