help50

help50 is a command-line tool with which you can get help understanding error messages in your terminal window. Rather than something you run yourself, it runs automatically: whenever a command fails, help50 looks at the command’s output. If it recognizes the error, it offers a hint in yellow right below it. If it doesn’t, and you’re in CS50 Codespace, it offers a help50 button atop your terminal window instead, which you can click to ask the CS50 Duck to explain the error.

For instance, were you to mistype ls as 1s, you would see

$ 1s
bash: 1s: command not found
Did you mean to run `ls` (which starts with a lowercase L)?

wherein the last line is help50’s hint. Or were you to try to compile hello.c with make hello.c instead of make hello, you would see

$ make hello.c
make: Nothing to be done for 'hello.c'.
Did you mean to run `make hello` instead?

And were you to run a command whose error help50 doesn’t recognize, you would see

$ cat nothere
cat: nothere: No such file or directory
🦆 Click `help50` above for help with that error.

along with a help50 button atop your terminal window. Click it, and the duck will be asked to explain what you ran and what happened. The button disappears once you’ve clicked it or run another command.

Among the errors that help50 recognizes are misspelled or miscapitalized commands, running a file instead of compiling it (e.g., ./hello.c), running a program that you haven’t recompiled since editing it, a cd or make or python that refers to a file or directory that’s in some other directory, check 50 instead of check50, and a Python file of your own (e.g., cs50.py) that “shadows” a module of the same name.

Usage

Nothing to run! Simply run commands as usual, and help appears when a command fails. help50 ignores commands that fail without any output (e.g., grep that finds no matches) and commands that you interrupt with control-c.

If you’re accustomed to running

help50 make hello

from earlier versions of help50, that still works: it simply runs make hello for you, and help appears as it would have anyway.

help50 also supports a few commands of its own:

Command Effect
help50 status Reports whether help50 is started or stopped in the current terminal window.
help50 stop Stops help50 in the current terminal window.
help50 start Starts help50 again in the current terminal window.
help50 disable Keeps help50 from starting in new terminal windows.
help50 enable Undoes help50 disable.
help50 is-enabled Reports whether help50 is enabled or disabled.

Installation

help50 is already installed for you in CS50 Codespace, so no need to install it yourself; simply use it as directed!

help50 is part of cs50/cli, CS50’s Docker image, so it’s also available via cli50, though without the help50 button (and thus the duck), which is a feature of CS50 Codespace.

Source Code