About me: My name is Solène Rapenne. I like learning and sharing my knowledge related to IT stuff. Hobbies: '(BSD OpenBSD h+ Lisp cmdline gaming internet-stuff Crossbow). I love percent and lambda characters. OpenBSD developer solene@.

Contact me: solene on Freenode, solene+www at dataswamp dot org or solene@bsd.network (mastodon). If for some reason you want to give me some money, I accept paypal at the address donate@perso.pw.

A few tips about the command cd

Written by Solène, on 04 September 2020.
Tags: #unix

Comments on Mastodon

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 $PWD

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