Navigating File Systems using the Shell

Files store the data you need to work with, so the shell needs to provide you with convenient ways of accessing and interacting with both your files and the folders that organise them. To achieve this, the shell has a working directory. This represents the folder that you are working with. You can execute shell commands to list the files within the working directory, move to new directories, and perform other operations on your files.

File Access Commands

You can directly access files within the current working directory, which we often just call the current directory. Let’s take a look at the main commands you need to get stared exploring files and manipulating the working directory in your terminal:

Action	Command	Description
Print Working Directory	pwd	Outputs the current working directory.
Change Directory	cd	Moves the shell to a different working directory (i.e., folder).
List Files	ls	Outputs a list of files in the current directory.

Print Working Directory (pwd)

The pwd command will let you know the path to the terminal’s current working directory. Give it a go in your terminal. Type pwd at the shell’s prompt, press enter to execute the command, and see the path to where you currently are.

pwd

Change Directory (cd)

Changing directory will require you to tell the shell where you want to go to. We call this passing information to a command. There are some conventions on how you pass information to comamnds which we will look at as we go through them.

The main way to pass data to a command is through an argument. In the shell, arguments are provided after the command name. You can pass 0, 1, or more arguments to a command, with each argument separated by a space.

Argument?

An argument is the term we use to provide data for a command to use. This is derived from the notion of mathematical arguments. When a command can be provided with an argument we say that it accepts the argument.

Read the friendly manual

The man shell command in Unix opens the manual for a given command. You pass man a single argument of the name of the command you want help with. So man pwd will give you the instructions on how to use the pwd command. This can be useful if you are stuck, though searching the internet or accessing Bard or other generative AIs can help too. Online versions of these manuals are also available. For example, you can use this to read about the cp command.

man pwd
# This will open the manual for the pwd command - press q to quit
man man
# This will open the manual for the man command - press q to quit

Here is an example on how the change directory command is used. This will change the current working directory into the folder at the /home path.

cd /home

The cd command takes one argument - the path to the directory you want to make the current working directory.

Tip

With many terminal programs, you can drag and drop files onto the terminal program to inject their path at the location of the cursor in the prompt.

Give it a try!

Use the following commands to move to the root of the file system, print out the working directory, then move back to your home folder and print out the working directory again.

cd /
pwd
# This will output > / (you are in the root folder)

cd /home/multitool
pwd
# This will output > /home/multitool (if you are using the username multitool)

Comments

These are all commands from the shell scripting language. Comments in this language can be written by starting the line with #. This tells the interpreter to ignore the text on that line, as it is not an instruction to the computer. Comments are very useful for leaving notes in your code for yourself or other programmers.

Caution

Sometimes you will receive back an error from attempting to execute a shell command. For example, if you provide cd with an invalid argument, such as a path that does not exist in your file system, you will see a message “cd: no such file or directory”.

Charlotte’s tip

Lots of beginners forget to read the output of their shell commands and sometimes don’t realise that they provided an invalid argument. This can be very confusing when they then input other commands assuming the earlier ones worked.

Pay attention to the output of your commands to make sure they are working!

Looking around

Moving folders is great, but we also need to be able to see what is in these folders.

Listing folder contents (ls)

Use the ls command to list the files in a folder. By default, ls lists the files in the current folder. Alternatively, you can pass in an argument for the path to the folder you want to list the contents of.

ls
# You should see a list of the files and folders in the current directory (folder)

In addition to arguments, many commands can also take options. These are arguments that start with a -. There are a number of options you can use to help format the output of the list command. One common set of options for ls is to use ls -lha. The l option asks for a long format list (one file per line), h asks for file sizes in human-readable numbers, and a asks for all files (including hidden files).

Note

Files in a computer can be visible or hidden. Hidden files are used to store information that most computer users do not need to access, and don’t show up in your graphical file navigation system (e.g., Finder on OSX or Explorer on Windows) unless you specifically change your settings to show them. They also do not show up when using ls unless you use the a option. The idea behind having hidden files is to avoid cluttering the display of directory contents with information most users would not find valuable. On OSX and Linux, the name of a hidden file always starts with ”.”

Give it a try!

Try running the following commands in your terminal. Compare the output of using ls with different options.

ls -l
# compare with the ls output

ls -lha
# check the file sizes and hidden files

You can also use arguments with wildcards to indicate the kind of file you want to list. Try ls -lha D* The * is a wildcard, meaning it can be replaced by anything. So D* will be any file or folder starting with the letter D.

Try moving around and exploring your file system. Go to the root and list the files and folders there. Then move into some of your folders and list what they contain. Look at a file in your graphical file explorer, and see if you can find the same file in the terminal.

Folder shortcuts

There are some shortcuts we can use in the shell to help move to common folders, and move between folders without having to type out the entire path from the root.

Going home (~)

To get back to your home directory, the one where your files are generally stored, you can either use the full path or the shortcut ~. The shell knows that you will often want to go to your home folder, so it added ~ as a shortcut.

Give it a try. Move back home using cd ~. Use pwd to check where you are.

cd /
pwd
# This will output > / (we are in the root folder)

cd /
cd ~
pwd
# This will output > /home/multitool (if you are using the username multitool)

Paths in Windows MSYS2

Remember that in MSYS2 the ~ shortcut will refer to your home folder in MSYS, not your Windows home folder. Unfortunately in MSYS2 you will need to use /c/Users/<username> anywhere you see ~ being used in shell commands.

Parent Folders (..)

How can you move to the parent of the current?

Once again you could use the full absolute path, but you could also use the convenient shortcut ... In the shell, . is a shortcut for the current directory and .. is the shortcut for the current directory’s parent.

cd /home
pwd
# This will output > /home

cd ..
pwd
# This will output > / -- the parent folder of home

Current folder (.)

There is also a shortcut to the current folder. This will be very useful later. You can use . to represent the current folder.

cd /home
pwd
# This will output > /home

cd .
pwd
# This will output > /home -- you moved to the current folder!

cd ./multitool
cd ./Documents
cd ./Code
pwd
# This will output > /home/multitool/Documents/Code

Relative paths

Shortcuts

To summarise, there are three really useful shortcuts:

• ~ is the path to your home directory.
• . is the path to the current working directory.
• .. is the path to the current working directory’s parent folder.

Using folder shortcuts, you can create relative paths. These are paths relative to the terminal’s current location. That is, they describe a path from your current location to another location within the file system. The following examples demonstrate the use of relative paths and folder shortcuts to navigate between sibling folders (folders with the same parent).

cd /home/multitool/Documents/code
pwd
# This will output > /home/multitool/Documents/code

cd ../presentations
pwd
# This will output > /home/multitool/Documents/presentations

Tip

If you don’t write an absolute path (i.e., start with /), and don’t start a path with one of the three shortcuts, the shell will assume you mean “from the current location”. So, cd Documents is the same as cd ./Documents.

You can combine multiple shortcuts together to navigate anywhere in your filesystem without using an absolute path:

cd /home/multitool/Documentations/presentations
cd ../../Downloads
pwd
# This will output > /home/multitool/Downloads

cd ~/Documents
# This will output > /home/multitool/Documents

cd ~/../other-user
pwd
# This will output > /home/other-user (assuming this folder exists)

Auto-complete

If you start typing part of a path, you can auto-complete it using the tab key. For example, cd ~/Doc<tab> should complete to become cd ~/Documents, assuming you have a Documents folder within your home directory. Practice using tab to auto-complete paths as you navigate your file system using the terminal. This will greatly increase the speed at which you can move around!