Step 3 - Challenge: Handling Non-Existent Commands | Step 3 - Non Existent Commands | Build Your Own Shell (Python Edition) | Products

Step 3 - Challenge: Handling Non-Existent Commands

In this step your goal is to handle non-existent commands.

Now that we can enter multiple commands and safely exit our shell, we want to ensure it is robust. That is, if the user tries to run a command that doesn’t exist our shell shouldn’t crash.

That should look something like this when it’s done:

% ccsh
ccsh> fubar
FileNotFoundError: [Errno 2] No such file or directory: 'fubar'
ccsh> exit
%

Build Your Own Shell (Python Edition)

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Step 0 - Setting Up

What We're Going To Build

Create a GitHub Repo

Setting Up Python

Step 1 - Create The Simplest Possible Command Line Shell

Step 1 - Challenge: The Simplest Possible Shell

Building The Simple Shell

Step 1 - Solution: The Simplest Shell

Step 2 - Challenge: Handle Multiple Commands

Step 2 - Challenge: Handling Multiple Commands

Exiting From The Shell

Handling Multiple Commands

Step 2 - Solution: Handling Multiple Commands

Step 3 - Non Existent Commands

Step 3 - Challenge: Handling Non-Existent Commands

Catching And Handling Errors

Step 3 - Solution: Handling Non-Existent Commands

Step 4 - External Commands With Arguments

Step 4 - Challenge: Commands With Arguments

Handling The Arguments

Step 4 - Solution: Handling The Arguments

Step 5 - Built-in Commands

Step 5 - Challenge: Implement Builtin Commands

Adding The Builtin Commands

Step 5 - Solution: Implementing Builtin Commands

Step 6 - Support Pipes

Step 6 - Challenge: Supporting Pipes

Approaching The Task Of Piping Commands

Piping Commands - The Walking Skeleton

Supporting Piping For Builtin Commands

Step 6 - Solution: Supporting Pipes

Step 7 - Handling Signals

Step 7 - Challenge: Handling Signals

Handling Signals In Python

Step 7 - Solution: Handling Signals

Step 8 - Command History

Step 8 - Challenge: Command History

Handling History

Some Refactoring - Pulling Out Builtins

The History Solution

Step 8 - Solution: Command History

Conclusion

Taking It Further And Wrapping Up