Weekly Unix #5 - cd

#linux
man cd
No manual entry for cd

That’s because there isn’t any! cd is an internal shell command.

So where do I find help?

Well there isn’t much in cd that you can do except change the directory. But since this operation is done hundreds of times a day, we need to do it efficiently.

cd -

cd with a hyphen goes to previous directory and executing that again comes back to current directory. It’s like a back button which can keep you toggling between two directories.

So next time you are switching between two paths again and again, use cd -

Bookmarking Important Locations

In a browser or in a file explorer, we can bookmark places we frequently visit. Same goes with command line. Though there is no one click solution to bookmark a location, but it’s not that hard either.

We can simply created aliases of important locations. For example, my workspace is at location ~/workspace and I navigate there a lot! So I have added the following lines in my.bashrc file.

alias bm_workspace="~/workspace"

So now every time, I have to go there, I simply type

cd $bm_workspace

In this example it looks like I have to type more than I would have typed earlier. But this trick is very helpful if you have a long directory path. Plus, when on terminal with auto-complete, I type $bm and press tab and all my bookmarks are shown for auto completion. All I have to press is w and tab again and I’ll be in workspace. If you have a long path like this:

alias bm_jboss_deployments="~/toosl/jboss-7.1.0/standalone/deployments/"
alias bm_blog="~/Documents/writings/blogposts/"

aliases are quite helpful. In the above case say you want to go to Jboss Deployments, all you got to type few characters and no more! Having a prefix like bm helps me to list all my bookmarks at once by typing bm_ and pressing tab if I ever forget them.

CDPATH variable

But what if the entire directory is important. All the folders and files in a particular directory. For example my Desktop has mostly important files and folders only and I navigate quite frequently to them. Or the user’s home directory is important.

Here comes in hand the CDPATH variable. CDPATH is the base directory for cd. Meaning - if the argument (directory you are trying to cd into) is not found in current working directory, it is searched in all the paths in CDPATH variable.

Advantage?

Well you don’t need to type the complete directory path. You just need to type the directory you want to cd into and you will be taken there. For example you are at home and there is a directory called workspace where there are multiple project folders and you have to navigate to one of the project folder. Traditionally you would navigate to the folder by typing the complete path. But with CDPATH you just need to type the folder name.

Here’s an article on CDPATH. It has examples and more details on the same. I’ll leave up to you to refer the said article without going into much details of CDPATH. But it’s one important trick you shouldn’t miss!

../../../.. umm what?

At times we need to go to parent directories or grand parent or great great grand parent of the current directory. ‘..‘ referes to parent of current directory and going to 4th parent of current directory or 5th parent is just tedious. With lots of dots and slashes and counting them, it just get’s confusing. To simplify this, I’ll share some simple aliases which if you create on your system, I’m quite sure you’ll have a hard time on navigating on some one else’s system because you will so much get used to them. Following is the list, add to your .bashrc and leave in peace from here onwards!

alias .='cd ..'
alias ..='cd ../..'
alias ...='cd ../../..'
alias ....='cd ../../../..'
alias .5='cd ../../../../..'
alias .6='cd ../../../../../../'

Want to go to parent?

.

Parent’s parent?

..

5th parent of current directory?

.5

You are there!! Once you start using this, you will regret why you didn’t know about this earlier!

I’ll conclude this cd article but will keep posting more on effective navigation.

TL;DR

  • cd - goes to previous directory
  • Use bookmarks for navigation
  • Set CDPATH for most frequent directories
  • Set parent aliases