P2-7.2 Terminal, Shell, and Working Directory¶

Section ID: P2-7.2 Version: v2026.07.20

In P2-7.1, we first looked at the place where code runs. Now we look at the first screen a reader usually meets when entering commands on a local PC.

When beginning programming, the following sentences appear often.

For example, introductory documents often contain sentences like these.

• Open the terminal and run it.
• Move to the project folder.
• Enter the command below.

These sentences are short, but several concepts are packed into them at once. If you cannot distinguish terminal, shell, command, and working directory, you often end up in the situation I definitely typed the same thing, so why is it not working?

Here we explain the basic distinction among terminal, shell, and working directory. Even when later Sections continue into Python execution, virtual-environment activation, and package-installation commands, the places where we type commands and the location from which they are interpreted reconnect on top of the explanation here.

Rather than learning every terminal feature by operating system, this Section focuses on building the minimum language needed to read and execute commands on a local PC. If you separate the roles of terminal, shell, and working directory here, then when you later see Python file execution, virtual environments, and package installation, you can first divide problems into code errors and location errors.

Core Criteria: Terminal, Shell, and Working Directory¶

• You can explain terminal as the screen where commands are entered and results are viewed.
• You can explain shell as the program that interprets and executes commands.
• You can explain that the words terminal and shell remain from older ways of using computers.
• You can explain working directory as the folder used as the current base by commands.
• You can explain why basic commands such as pwd, cd, and ls or dir are needed.
• When a command fails, you can first divide the issue into a code problem or a location problem.

Three Criteria¶

Why Do the Words Terminal and Shell Still Remain?¶

Terminal and shell are not names of recently created apps. Both keep traces of the era when many people used computers through text.

The early terminal was not an app inside a laptop like today. It was an input-output device connected to a central computer. Text-Terminal-HOWTO explains that real text terminals looked like a monitor and keyboard but displayed not pictures but a text-based command-line interface, and that they were widely used for connecting to mainframe computers in the late 1970s and 1980s. Later, real hardware terminals decreased, but today's terminal apps are closer to terminal emulators that imitate that behavior in software.

Shell is also an old concept. The GNU Bash manual explains that Bash is the shell, or command language interpreter, for the GNU operating system. It also explains that a Unix shell is both a command interpreter and a programming language.

You do not need to memorize the whole history. If you remember the flow below, you can explain why the words terminal and shell remain.

• past: people entered commands to a central computer through a separate terminal device
• present: terminal apps provide that text-based way of working through software
• shell: the program that interprets and executes the command entered by the user

That is why expressions such as open the terminal, run it in the shell, and type it on the command line remain even in modern development environments. All of these are connected to the flow instead of pressing graphical buttons, enter commands as text and execute them.

The Terminal Is the Screen, and the Shell Is the Program That Interprets Commands¶

The terminal is the screen where commands are entered and results are viewed. Terminal on macOS, Windows Terminal, and the Terminal panel in VS Code belong here.

The shell is the program that reads, interprets, and executes the commands entered by the user. Through the shell, the user can run and combine many utilities of the operating system.

Here we distinguish them like this.

• terminal: the window where commands are entered and results are viewed
• shell: the program inside the terminal that reads and executes commands
• command: the thing we ask the shell to do

So even inside the single phrase I opened the terminal, there are several cases.

Here we do not go deeply into differences among shells by operating system. But we try to mark what the command examples are based on.

A Command Is Not a Sentence, but an Execution Request¶

The sentence entered in the terminal is not a natural-language sentence. It is an execution request that the shell reads according to fixed rules.

For example, the following is a command that checks the current location.

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pwd

The next command moves to a folder.

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cd docs

The next command looks at the file list of the current folder.

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ls

In Windows PowerShell, Get-Location can be used to check the current location, and Set-Location can be used to move. Microsoft documentation explains that Get-Location displays the current location and that Set-Location sets the current working location.

You do not need to memorize all commands. What matters is where the command is executed.

The same command can target different files when the current folder is different.

The Working Directory Is the Base Location of a Command¶

The working directory is the folder currently used as the base by a command. It is also called the current working directory (CWD).

For example, suppose the following command is executed in the terminal.

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python example.py

This command can usually be read as, find the file called example.py in the current working directory and run it with Python. But if there is no example.py in the current working directory, the command fails.

Did it fail because the file does not exist? Not necessarily.

In a common case, the file is not absent. The file exists, but I am in the wrong folder.

A common error begins not from code syntax, but from a location problem. The file may be in downloads/, but the terminal may be in home/. The project folder may be in project-name/, but the terminal may be in its parent folder.

So before practice, we check the current location.

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pwd

Then we move to the needed folder.

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cd /Users/someone/ws/project-name

In Windows PowerShell, you can check it like this.

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Get-Location

And move like this.

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Set-Location C:\Users\someone\ws\project-name

Even if the command names differ, the core is the same.

So first check these two questions.

• In what folder am I now?
• On what folder does this command execute as its base?

Distinguish Relative Paths and Absolute Paths¶

A path is the string that indicates the location of a file or folder. Here we distinguish relative path and absolute path.

The two terms are distinguished as follows.

• relative path: a location found based on the current working directory
• absolute path: the full location written starting from the beginning of the file system

For example, if the current working directory is /Users/someone/ws/project-name, then the following relative path can point to the documents folder.

For example, docs/parts is a relative path.

By contrast, an absolute path writes everything from the starting point.

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/Users/someone/ws/project-name/docs/parts

Relative paths are short and convenient. But if the current working directory changes, their meaning changes too.

docs/parts has meaning when executed inside the project-name folder. But if it is executed from another project folder, it points to a completely different location or to a path that does not exist.

The Habit of Checking the File List Matters¶

When a command fails, before immediately editing the code, check the current folder and the file list.

In Unix-like shells, the following commands are usually used.

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pwd
ls

In Windows PowerShell, the following commands can be used.

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Get-Location
Get-ChildItem

In PowerShell, ls often works as an alias of Get-ChildItem. But it is still helpful to look once at the original name rather than only the alias. Later, when searching documentation, you can search using the official name.

Here we first show commands based on macOS/Linux, and if Windows needs a different command, we mark it separately.

Is There No Terminal in Colab?¶

Colab can also execute commands. But misunderstanding appears if it is understood as exactly the same thing as the local PC terminal.

If you put ! like the following inside a Colab code cell, you can execute a shell command.

Problem situation: we see that even inside a Colab code cell, a shell command checking the current working location can be run. Input: the !pwd command executed in a code cell. Expected output: the current folder path is printed based on the Colab runtime. Concept to check: the ! command in Colab runs a shell command in the Colab runtime, not in my PC terminal.

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# This shell command checks the current working folder from a Colab code cell.
!pwd

At that time, the command is executed not on my laptop computer, but in the Colab runtime. So the file location, installed packages, and saved files can differ from the local PC.

In summary, it is as follows.

• terminal of my PC: executed on the basis of my computer's files and environment
• ! command in a Colab code cell: executed on the basis of the Colab runtime's files and environment

This is also why in P2-3.5 we distinguished !pip install numpy from %pip install numpy. Even if shell commands can be executed inside a code cell, that does not mean they are Python syntax.

Errors That Often Happen in the Terminal¶

Even when terminal errors look complicated, they can be divided into a few types.

This Section does not solve every error. But it builds the habit of dividing, when reading an error, between an error in the code itself and an error in the location where the command was executed.

View It Through a Case¶

Case 1. Why python example.py Fails Even Though the File Exists¶

Suppose a learner downloaded the file example.py and is trying to run it. The file definitely exists inside the project folder on the desktop, but when python example.py is entered in the terminal, an error appears saying that the file cannot be found.

People often first think, Was the file broken? or Is Python strange? But in this case, a more common cause is that the current working directory is not the project folder. The same command can look for a completely different file depending on from what folder it is executed.

If we distinguish the core words of this Section, terminal, shell, working directory, and relative path, the interpretation changes. The problem may not be the code itself but from what location the command was executed as its base, and that is why commands such as pwd, ls, and cd are needed first.

The confirmable result appears immediately when the current location is printed. If the result of pwd is not the project folder, then the reason the same python example.py command fails can be explained not as a code issue but as a location issue.

Checklist¶

• You can explain the terminal as the screen for command input and result checking.
• You can explain the shell as the program that interprets and executes commands.
• You can explain that terminal apps inherited in software the role of older text-based terminal devices.
• You can explain the working directory as the current base location of commands.
• You can explain the difference between relative path and absolute path at an introductory level.
• You can explain why pwd, cd, and ls are needed.
• You know that in PowerShell, official command names such as Get-Location, Set-Location, and Get-ChildItem exist.
• You can explain that the ! command in a Colab code cell is executed in the Colab runtime, not on the local PC.
• You can first check what shell am I using, what folder am I in now, and what file or program is this command trying to find.

Sources and References¶

• David S. Lawyer, Text-Terminal-HOWTO, The Linux Documentation Project, checked 2026-07-20. Used as historical support for the relationship between older text terminals and modern command-line interfaces.
• Free Software Foundation, Bash Reference Manual, GNU Bash 5.3 manual, checked 2026-07-20. Used to confirm that a shell is both a command interpreter and a programming language, and to support the Bash command-processing context.
• Microsoft, Get-Location, PowerShell documentation, checked 2026-07-20. Used to confirm the official PowerShell command for checking the current working location and its pwd alias context.
• Microsoft, Set-Location, PowerShell documentation, checked 2026-07-20. Used to confirm the official PowerShell command for changing the current working location and its cd alias context.
• Python Software Foundation, os.getcwd, Python 3.14.6 documentation, checked 2026-07-20. Used to support the point that Python code can read the current working directory as a string.