Title: A few tips about the cd command

	Title: A few tips about the cd command
	Author: Solène
	Date: 04 September 2020
	Tags: unix
	Description:

	While everyone familiar with a shell know about the command `cd`
	there are a few tips you should know.

	### Moving to your $HOME directory

	$ pwd
	/tmp
	$ cd
	$ pwd
	/home/solene

	Using `cd` without argument will change your current directory to
	your $HOME.


	### Moving into someone $HOME directory

	While this should fail most of the time because people shouldn't allow
	anyone to visit their $HOME, there are use case it can be used though.

	$ cd ~user1
	$ pwd
	/home/user1
	$ cd ~solene
	$ pwd
	/home/solene

	Using `~user` as a parameter will move to that user $HOME directory,
	note that `cd` and `cd ~youruser` have the same result.


	### Moving to previous directory

	This is a very useful command which allow going back and forth between
	two directories.

	$ pwd
	/home/solene
	$ cd /tmp
	$ pwd
	/tmp
	$ cd -
	/home/solene
	$ pwd
	/home/solene

	When you use `cd -` the command will move to the previous directory
	in which you were. There are two special variables in your shell:
	`PWD` and `OLDPWD`, when you move somewhere, `OLDPWD` will hold
	your current location before moving and then `PWD` hold the new
	path. When you use `cd -` the two variables get exchanged, this
	mean you can only jump from two paths using `cd -` multiple times.

	Please note that when using `cd -` your new location is displayed.


	### Changing directory by modifying current PWD

	thfr@ showed me a cd feature I never heard about, and it's the
	perfect place to write about it. Note that this work in ksh and zsh
	but is reported to not work in bash.

	One example will explain better than any text.

	$ pwd
	/tmp/pobj/foobar-1.2.0/work
	$ cd 1.2.0 2.4.0
	/tmp/pobj/foobar-2.4.0/work

	This tells `cd` to replace first parameter pattern by the second
	parameter in the current `PWD` and then cd into it.

	$ pwd
	/home/solene
	$ cd solene user1
	/home/user1

	This could be done in a bloated way with the following command:

	$ cd $(echo $PWD \| sed "s/solene/user1/")

	I learned it a few minutes ago but I see a lot of uses cases where
	I could use it.


	### Moving into the current directory after removal

	In some specific case, like having your shell into a directory that
	existed but was deleted and removed (this happens often when you
	working into compilation directories).

	A simple trick is to tell `cd` to go to the current location.

	$ cd .

	or

	$ cd $PWD

	And `cd` will go into the same path and you can start hacking
	again in that directory.