Learning · online tutorial
Twelve Days of Shell
A free, browser-based set of challenges that lets people practice command-line skills without setting up full projects. Critics say the answer checker often rejects valid commands and gives no output on wrong answers.
Summarized from 20 comments.
A free, browser-based set of challenges that lets people practice command-line skills without setting up full projects. Critics say the answer checker often rejects valid commands and gives no output on wrong answers.
- recommend
- 6
- criticize
- 11
- months recommended
- 1 of 13
What people warn about
Rejects valid commands as wrong · 4
I think a beginner could be doing it right but then be told they are wrong as you aren't evaluating actual commands
Dec 2025 · commentIt accepts ls -a as and answer and ls -l but not ls -al
Dec 2025 · commentit's rejecting valid commands as incorrect
Dec 2025 · commentShows no output on wrong answers · 2
You don't see the (wrong) output if you don't get it right the first time
Dec 2025 · commentDoesn't tell you without looking at the answer.
Dec 2025 · commentWeak shell escaping handling · 2
But doesn’t seem to do enough shell escaping or correctly.
Dec 2025 · commentdoesn’t seem to do enough shell escaping or correctly.
Dec 2025 · commentUnclear which previous problem applies · 2
It's difficult to know that it is following from the previous problem
Dec 2025 · commentThat's pretty confusing especially since users are primed with file contents from the previous exercises already.
Dec 2025 · comment
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Every quote
The 20 most detailed of 20 comments. Each links to the original.
You don't see the (wrong) output if you don't get it right the first time
Mixed · Dec 2025 · in “Twelve Days of Shell”
It's difficult to know that it is following from the previous problem
Mixed · Dec 2025 · in “Twelve Days of Shell”
But doesn’t seem to do enough shell escaping or correctly.
Mixed · Dec 2025 · in “Twelve Days of Shell”
I think a beginner could be doing it right but then be told they are wrong as you aren't evaluating actual commands
Criticizes · Dec 2025 · in “Twelve Days of Shell”
That's pretty confusing especially since users are primed with file contents from the previous exercises already.
Criticizes · Dec 2025 · in “Twelve Days of Shell”
It accepts ls -a as and answer and ls -l but not ls -al
Criticizes · Dec 2025 · in “Twelve Days of Shell”
doesn’t seem to do enough shell escaping or correctly.
Criticizes · Dec 2025 · in “Twelve Days of Shell”
Doesn't tell you without looking at the answer.
Criticizes · Dec 2025 · in “Twelve Days of Shell”
it's rejecting valid commands as incorrect
Criticizes · Dec 2025 · in “Twelve Days of Shell”
it also doesn't accept the find command.
Criticizes · Dec 2025 · in “Twelve Days of Shell”
when you make a mistake then the name of the file you have to use disappears and it's impossible to get it back
Mixed · Dec 2025 · in “Twelve Days of Shell”
Nice way to level up your CLI muscles without diving into full projects.
Recommends · Dec 2025 · in “Twelve Days of Shell”
It does seem to actually run the submitted commands, and awk is there.
Recommends · Dec 2025 · in “Twelve Days of Shell”
The tab completion sorta works but it seems to be simulated, doesn't understand subdirectories etc.
Criticizes · Dec 2025 · in “Twelve Days of Shell”
Terrible. You cannot 'ls' if ls is not the right answer. Completely useless.
Criticizes · Dec 2025 · in “Twelve Days of Shell”
Still doesn't work for me in a new session separate browser.
Criticizes · Dec 2025 · in “Twelve Days of Shell”
the questions stopped showing up after the second challenge
Criticizes · Dec 2025 · in “Twelve Days of Shell”
It doesn't handle backspace correctly.
Criticizes · Dec 2025 · in “Twelve Days of Shell”
This is more annoying than fun.
Criticizes · Dec 2025 · in “Twelve Days of Shell”
No it still doesn't work.
Criticizes · Dec 2025 · in “Twelve Days of Shell”
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