If you’re like most developers, DevOps engineers, or IT professionals, you probably spend a lot of time in your shell of choice. And if you’re like the typical user, you’re probably always deep in the filesystem. This can get confusing quickly, and there’s only so much space available to display your working path (unless you invest in an ultrawide monitor, but even those have limits).

So in this post we will be looking at hash to shorten some of those paths’s.

So what’s this all about

In this example, we will use the path /home/user/baseDir as an example with 3 subdir’s setup. Let’s assume we have this setup:

baseDir
  ∟ Work
  ∟ Personal
  ∟ Downloads

Now, if you’re in any of these folders, your shell path will look like this:

$ /home/user/baseDir/Work

That’s pretty readable, but if you’re working in a project, and then a directory, and the subfolder of that directory things might quickly look like this:

$ /home/user/baseDir/Work/BigImportantProject/FolderWithPictures/PicturesOfParty

Now that’s a long dir.

We will use hash to set up more readable paths for these three directories. Then, I will demonstrate some additional options this enables.

What is hash used for?

Well!

The /usr/bin/hash utility affects the way the current shell environment remembers the locations of utilities found. Depending on the arguments specified, it adds utility locations to its list of remembered locations or it purges the contents of the list. When no arguments are specified, it reports on the contents of the list. The -r option causes the shell to forget all remembered locations.

Utilities provided as built-ins to the shell are not reported by hash.

– StackExchange2023 ¹

Thanks StackExchange!

Shortening paths

hash can be used to shorten path’s with the following command:

hash -d ALIAS="/path/to/folder"

For example, we will shorten the path /home/user/baseDir/Work to Work like this:

hash -d Work="/home/user/baseDir/Work"

This will turn your shell path from /home/user/baseDir/Work to ~Work when you are in that directory. That’s really great. You can now easily see that you’re in your “Work” folder, giving you a better understanding of your system’s structure.

Example of shortening shell path when entering directory

But wait! Theres more!

Permanence

Aliases are only valid for the current session, so if you want to make them permanent you can add them to your .bashrc or .zshrc:

# /home/user/.zshrc
....
hash -d Work="/home/user/baseDir/Work"  
hash -d Personal="/home/user/baseDir/Personal"
hash -d Downloads="/home/user/baseDir/Downloads"

Bonus one: Navigation

Set up aliases to easily navigate to them. For example:

$ cd ~Work

Moving to hashed dir from anywhere by using ~ALIAS

You can also use tab completion to easily navigate to sub folders.

Bonus two: Easy copy

ANother thing hash aliasses enable is easy copying of files. For example, you can copy a file from any place to your Work directory with:

$ cp FILE ~Work

This makes it easy to copy files from ~Downloads to ~Work. You could for example move a downloaded pdf easliy like:

$ cp ~Downloads/TheExpanseRapport.pdf ~Work

And this works from anywhere on your system.

Example of moving a file to a folder that is hashed

Conclusion

We can use hash to make our terminal usage more clear and organized. If you are like me and work with a pretty rigged folder structure like PARA ² then you know how nice it is to be able to jump to Projects, Areas and Resources quickly.