Twelve Days of Shell

(12days.cmdchallenge.com)

215 points | by zoidb 11 hours ago ago

72 comments

  • aargh_aargh 10 hours ago

    The good: Nice exercises for beginners. Tab-completion, accepts readline characters like ctrl-u.

    The bad: You don't see the (wrong) output if you don't get it right the first time, making it hard to work iteratively and having to guess what the question actually intended.

    E.g. 'Seven files that start with "Santa"' actually wants file names that start with Santa, after some questions that had you use "grep" to search file contents. Where I actually struggled with what's expected is Day 11.

    The ugly: Actually a very nice design.

    • pekim 5 hours ago

      > Where I actually struggled with what's expected is Day 11.

      Just the lines from the files are wanted, not the files names. It took me a little while to cotton on to that.

      Semi-spoiler follows.

      So you need to use the appropriate flag with grep to suppress the file names.

    • Retr0id 6 hours ago

      The tab completion sorta works but it seems to be simulated, doesn't understand subdirectories etc.

  • oneeyedpigeon 9 hours ago

    I think the instructions need more detail. 'Five lines that start with "the"' doesn't scream 'or "The", or "thE"' to me...

  • bArray 8 hours ago

    Great idea, but a few feedback points:

    1. It's difficult to know that it is following from the previous problem, and then on some problems it changes the workspace.

    2. It's not always easy to know what it wants.

    3. The question about finding a line starting with "The" I successfully cheated:

         cat night-before-christmas.txt | grep "The "
    
    4. Likewise the ending "!":

        cat night-before-christmas.txt | grep "!"
    
    5. On the eighth day I get a "runner error" with the command:

         mv *lve* Workshop
    
    I'm globbing for the filename match, I'm not sure if it's "elve" or "Elve" and then trying to move to the target directory.

    Otherwise it's quite fun - the instant feedback is great.

    • iN7h33nD 4 hours ago

      iirc Elves is a directory with them inside.

  • arionmiles 10 hours ago

    I've recently reached a point where I feel I've reached an upper limit with how much efficiency I can extract from my usual toolset/editors. So I've gone on a journey where I'm finally exploring tools that make living in the command line a productive and pleasant experience for me.

    I've long put off learning or even exploring tmux or learning more than a few handful of vim keybinds. So I started digging into configuring them and learning them well enough to be able to regularly use them for work and personal computers.

    It's been very pleasant, to say the least. There's still a few ways I need to go where I do everything from the command line and the keyboard, but I think it's worth training your muscles to be comfortable with doing things purely using the keyboard.

    I've switched to vim mode for a few tools that offer it. I started seriously using vimium on chrome and firefox (a friend had introduced me to it about 7 years ago but I never cared enough to learn it well).

    Another reason I finally made the jump was that I've been having RSI pain on my right hand due to using mouse too much and in un-ergonomic positions. While I've taken measures to improve ergonomic use of the mouse and keyboard, I'm just totally impressed with the capabilities of keyboard navigation and how much value you can extract out of your keyboard.

    My friends have been egging on me about the bell curve meme, but I think it's important for me to figure out the limits and then maybe I will finally go back to defaults and simpler tools. The only way to be on the right side of the bell curve is through the middle.

    • Izkata 2 hours ago

      I have an odd suggestion for learning more of vim: Check out gvim.

      It's vim with a GUI, dropdowns for nice discoverability and most importantly the shortcuts on each menu item are the commands to use it in regular vim. It's how I found out vim even had folding waaay back.

      For Firefox, I use Tridactyl. After Vimperator died I tried several replacements and found Vimium very limited (IIRC it was the one that was just hotkeys and didn't have modes like vim, no idea how it's grown since then). I have Tridactyl configured to open gvim with the contents of any text input when I hit ctrl+i so I can use vim for them.

    • ratrocket 3 hours ago

      Not commenting on the larger gist of the comment, only:

      > I've been having RSI pain on my right hand due to using mouse too much and in un-ergonomic positions

      If you can, try using a left-hand vertical mouse. I use an Evoluent but there are a million brands. Get a cheapo and try it out. I figure it took me about a week to adjust and my wrists have been happier ever since.

    • kalaksi 10 hours ago

      For learning vim, I recommend searching for a "vim cheat sheet" that has an image of a keyboard layout with vim commands in it and printing that. Makes it easier to check and learn more, little by little.

      Another one is online tutorials that make you practice interactively. Haven't used those much but the little I did, it was helpful.

    • johncoltrane 8 hours ago

      Forget cheatsheets, tweets, videos, books, etc. Vim comes with a very well made built-in tutorial that will gently pull you toward maximum efficiency.

      • arionmiles 8 hours ago

        I love vim tutor!

        I learnt the basics of vim navigation through it. I'm yet to finish it since I dropped it after the first chapter to start using it as a daily driver and picking things as I need. I will probably come back and go through it again at some point and by then it will be another mind-blown situation

      • sambaumann 5 hours ago

        been using vim for years, just did the tutorial and learned several things I did not know

    • kace91 10 hours ago

      I went back and forth over the years with vim. Lazyvim plus the ebook (lazyvim for ambitious devs or something like that, it’s free online) is what allowed me to stick.

      I can’t be doing real work and suddenly realize I don’t know the way to do a certain basic action. Lazyvim makes it so that for everything you want to do, there’s an already configured way, and then you have all the time in the world to fiddle for a better alternative if you don’t like it.

  • lcuff 4 hours ago

    I thought there was too much ambiguity to several of the challenges:

    I gave up after the following exercise:

    On the eighth day of Shell my true love gave to me Eight elves in Santa's Workhop/ ... Hint: Try finding files named after Elves and moving them to the Workshop/ directory.

    It turns out, all they want is the files in the ./Elves directory to the ./Workshop directory. But I didn't figure that out.

    • imp0cat 40 minutes ago

      You're overthinking it. You can get quite far with a bit of ls or find . -type f exploration

  • derrida 10 hours ago

    Hey this doesn’t work : first solution “ls -al” which I use all the time to list directories was rejected in the second question I used awk and was rejected it expected grep

    I think a beginner could be doing it right but then be told they are wrong as you aren’t evaluating actual commands

    Best would be to like actually run it* and then check solutions out with awk that it pattern matches

    * aka give me a shell ok worth a try lol xD

    Edit: also I was expecting something a bit more challenging (also that is correct) to like exercise the brain for those of us that use shell (this is hacker news) something that takes a few minutes and isn’t just commands used all the time

    • comprev 8 hours ago

      "ls" shows only visible files whereas "ls -a" also displays those starting with a dot. Given the question doesn't that make your answer the correct one?

      • zenoprax 6 hours ago

        `la -A` will also show hidden files but excludes the "." and ".."

        I prefer that way in theory but a capital "A" is not as quick/easy to type.

      • derrida 6 hours ago

        It accepts ls -a as and answer and ls -l but not ls -al

    • Retr0id 6 hours ago

      It does seem to actually run the submitted commands, and awk is there.

      • derrida 5 hours ago

        Second question

        > awk '/^laugh/ { print $0 }' night-before-christmas.txt

        • aidenn0 5 hours ago

          Get rid of the caret and it works; it wants lines with laugh, not lines that start with laugh,

    • prmoustache 3 hours ago

      it also doesn't accept the find command.

  • blenderob 8 hours ago

    Looks nice but it's rejecting valid commands as incorrect. Like when it told me to search for "laugh" I ran

      grep laugh *
    
    There's only one file in the directory. So that's a correct answer but the game wants me to run

      grep laugh night-before-christmas.txt 
    
    It's like those weird interviewers who have a specific answer in mind and they'll accept nothing other than the answer they have in mind.
    • charlie-83 8 hours ago

      `grep laugh *` worked for me

      • blenderob 7 hours ago

        I tried again to see if they fixed it. No it still doesn't work. You'll get the output but look closer.

          Output does not match expected lines - try again
        
        So you can't move on to the next level.
        • szszrk 7 hours ago

          they must have fixed it. Works for me, including new sessions on separate browser.

          • blenderob 7 hours ago

            Still doesn't work for me in a new session separate browser. I get the output but I also get this message

              Output does not match expected lines - try again
            
            Does it give you the clue for the next level? Can you or someone else share a screenshot or something so I can compare to find out what I'm missing?
            • szszrk 7 hours ago

              For clean session it goes to the next level.

              There is some mess if you already finished the thing, and then use url to particular level on a clean session. For me it looked like I am on level 2, but site expected answers to 1.

              When I start from scratch with proper link (main page) simple:

              grep laugh *

              works

    • ggirelli 8 hours ago

      Or cat night-before-christmas.txt | grep laugh

  • janmatejka 9 hours ago

    'Seven files that start with Santa' is actually about filenames. That's pretty confusing especially since users are primed with file contents from the previous exercises already.

    And from pipers piping description I had no idea what was wanted of me.

  • throw0101d 8 hours ago

    Meta: the first day of the Twelve Days of Christmas is Christmas Day (December 25) itself:

    * https://en.wikipedia.org/wiki/Twelve_Days_of_Christmas

    The days before the 25th are part of the season of Advent:

    * https://en.wikipedia.org/wiki/Advent

    • xnorswap 8 hours ago

      Too many people I know spend their boxing day packing up their tree. Christmas is over before it's barely begun!

      But that's kind of understandable when Christmas begins in September if you believe the retailers.

      • throw0101d 6 hours ago
      • lo_zamoyski 4 hours ago

        Indeed. Christmas lasts until Epiphany (January 6th) or even Candlemas (February 2nd).

        Commercialism is likely the culprit for the current state of affairs. By putting the "Christmas season" and the commercialized variety of festivity before Christmas and making Christmas day the big finale, you create a situation during which you can get people to buy, buy, buy. And then it's over.

        Compare that with the real deal and as it was traditionally celebrated. Advent is a period of contemplation, waiting, quiet, abstinence from meat -maybe even fasting - in anticipation for the birth of Christ. Then, on Christmas Eve and especially Christmas day, the festivities kick off, and they last until January 6th (the 12 days of Christmas) or Candlemas (40 days of Christmas). And that's when people used to pack up their trees and decorations (either Jan 6th or Feb 2nd).

        People today suck at festivity. We're boring.

        • throw0101d an hour ago

          > Indeed. Christmas lasts until Epiphany (January 6th) or even Candlemas (February 2nd).

          Up to Candlemas was probably more cultural than liturgical, as things go back to 'Ordinary time' in the West post-Epiphany:

          * https://en.wikipedia.org/wiki/Christmastide

          * https://en.wikipedia.org/wiki/Liturgical_year#Christmastide

          * https://en.wikipedia.org/wiki/Epiphany_(holiday)

        • OkayPhysicist 3 hours ago

          IMO, commercialism moreso moved into the empty husk left after the Calvinists got to holidays, especially the puritanical sects that took root in the US. Specifically, I blame double-predestination: if you tell a bunch of people with free will that everyone is sorted into two groups, one going to heaven, one going to hell, and that the people going to heaven behave a certain way, it creates a much more oppressive, all-encompassing culture than traditional Christian "apologize and go to heaven because Jesus loves you" teachings. If your concern is not being judged negatively in the afterlife, you basically just need to follow some rules, try to be a generally good person, and you're generally free to do whatever else that isn't covered in the above categories. If you're concerned about demonstrating to others in your community that you are one of the God's chosen, who behave a certain way, that necessarily becomes universal factor in your life, which keeps escalating with time. This preoccupation with not being perceived as "having to much fun" so-to-say killed festivals.

  • ilvez 4 hours ago

    Constantly hit Ctrl-w and close the tab. Ctrl-Shift-Tab to get back to it :-) God bless saved state, otherwise I would not have completed :D

  • beardyw 10 hours ago

    As a developer I've been through 10 different languages and about the same number of operating systems, and I barely managed to remember any of them, even at the time. And I assume soon using natural language as the main interface will become commonplace, which will finally let me off the hook.

    I will give this a go, but I doubt any of it will stick!

    • k_bx 9 hours ago

      Shell quotes is the last frontier LLM's seem to keep getting wrong. Esp when it's Github CI yaml which needs to ssh somewhere and run command running another command there. Needs AGI apparrently.

  • cornonthecobra 7 hours ago

    It doesn't handle backspace correctly. The character is erased visually, but not removed from the buffer, so when you type the next character, the erased character reappears. Make one typo and you have to reload the page.

  • 6LLvveMx2koXfwn 6 hours ago

    "Try sending the command ls in the command box to list all files in the directory."

      My answer: `ls -a`
    
    er, wrong. Then don't put all in the question!
  • haolez 8 hours ago

    The way that worked for me to properly learn shell is to do a non-shell project with it.

    Like, do a complex background worker for a web server that listens to a socket, does complicated stuff, exports functions (if in Bash), etc.

    You don't have to use it afterwards. The value is in the journey. It's fun :)

  • Barathkanna 10 hours ago

    Fun idea. It’s basically an Advent calendar for shell one-liners. Nice way to level up your CLI muscles without diving into full projects.

    • jll29 10 hours ago

      Neat.

      Perhaps it would be even nicer if the "advent" theme was more prominently present, e.g. using the Bible as the target data file to be used.

      Here's three examples tasks from me:

      (1) Write an sh script (using only POSIX standard commands) to create a Keywords in Context (KWIC) concordance of the new testament.

      (2) Write a bash script that uses grep with regular expressions to extracts all literal quotes of what Jesus said in the New Testament. [Incidentally, doing this task manually marked the beginnings of philology and later automating it marked the beginning of what was later called literary and linguistic computing, corpus linguistics, computational linguistics, and digital humanities.]

      (3) How many times is Jesus mentioned by each of the four accounts of his life (Matthew, Mark, Luke, and John)?

      (You may begin by extracting the New Testament from the end of the Bible with a grep command.)

      Dataset: https://openbible.com/textfiles/kjv.txt

      • chrisweekly 8 hours ago

        Respectfully, many would find that off-putting. "Advent of X" in tech is entirely decoupled from religion. Keeping it neutral seems to me the "nicest" approach. That said, something like what you described might be a cool exercise for your bible study group. Finally, I appreciated your "incidentally" aside about the origins of philology.

        • lo_zamoyski 4 hours ago

          I'll preface this by saying I was never especially bothered or moved by the non-religious use of "Advent of X", for better or for worse. In fact, my remark is inspired only by your comment, concerning its consistency and who has the stronger case.

          Specifically, while it is true that certain kinds of words can become decoupled from their original meanings (which is generally normal), in this case, the usage is not so decoupled, especially given that this usage occurs during the religious season of Advent and with the intentional allusion to the religious season of Advent. (Otherwise, what is "Advent of X" without its religious origin and which takes place at the exact same time during the year?)

          You can make a much stronger argument that the non-religious usage is a kind of cultural appropriation. That would make your concern entirely backwards. Your wish is to keep it "neutral" to please those who don't practice Advent, as you show a simultaneous lack of concern for the tradition it appropriates from. This involves a tacit claim of possessing the authority to do so as well, but if anything, given the source, if anything, the authority belongs not to the appropriators, but to the Church.

          One wonders how a "Ramadan of Code" or "Teshuvah of Shell" would be received.

          "Neutrality" is, of course, a bunk concept, and the idea that we ought to be guided by what is "nice" rather than what is "good" is a grave misunderstanding of how decisions ought to be made.

  • mejthemage 5 hours ago

    I would love something like this that puts me in my own shell. Like a light CTF that is really just shell commands rather than breaking into a VM

    • mejthemage 5 hours ago

      I went searching and realized overthewire has a bash specific course called "Bandit". Still a VM you SSH to

  • lozf 4 hours ago

    If you like things like this you'll probably enjoy

         b64(r13(MaE3o3OmYz5yqPNtqUu0VPOxnJpX))
  • sannysanoff 9 hours ago

    Fluent in shell, but cultural context is more difficult, especially with pipers, had to do guess work.

    • ggirelli 8 hours ago

      I think that's part of the fun :)

  • FailMore 8 hours ago

    How would one make a true shell in a website like this one? (As in, is there an open source library to host an interactive shell for educational purposes - eg codecademy)

    • ctippett 6 hours ago

      I couldn't tell you the exact details (I'm only passingly familiar with how it works myself), but you'd almost certainly want to start by looking into web assembly.

      I found a-Shell's documentation[1] quite interesting, it describes their use of web assembly and offers some practical tips for compiling stuff so it can work in a sandboxed environment.

      [1]: https://bianshen00009.gitbook.io/a-guide-to-a-shell/lets-do-...

  • entropie 3 hours ago

    I have serious issues reading that font

  • benterix 10 hours ago

    It would be nice if the instructions spelled out what to do, then I could do it. Otherwise I have to guess what author meant. But all in, a nice small exercise, thanks!

  • pstoll 10 hours ago

    Neat idea à la regex golf.

    But doesn’t seem to do enough shell escaping or correctly. Also seems underspecified, ie “find 5 lines starting with ‘the” doesn’t require a pipe to head -5.

    • oneeyedpigeon 9 hours ago

      > find 5 lines

      Especially since the previous two questions used head/tail. IMO, the wording would be better as "find all the lines" since that's what the command does.

  • naikrovek 2 hours ago

    I use the shell all day every day and I got stopped at the SECOND question.

    "lines that contain 'laugh'". lines of what? Doesn't tell you without looking at the answer.

    genius.

  • smusamashah 7 hours ago

    That font is not very easy to read quickly.

  • sva_ 9 hours ago

    Cool idea but very opinionated and no room for variation

  • franticgecko3 10 hours ago

    Tab complete is completely broken on Firefox mobile (Android)

  • ParadisoShlee 9 hours ago

    I assumed this was some kind of hacking challenge.

  • Biganon 7 hours ago

    I mean if you ask for the lines that start with "the" and expect lines that start with "The", maybe you should say it in the instructions.

    After the 3rd time I had to peek at "learn" to understand what was even asked, I gave up. This is more annoying than fun.

  • bluecalm 10 hours ago

    It looks very nice. One problem I've encountered is that when you make a mistake then the name of the file you have to use disappears and it's impossible to get it back. What is this website created with btw? I like the style a lot.

  • skinwill 10 hours ago

    Viewing the page with Safari 26.1 the questions stopped showing up after the second challenge. I was left with only Learn and View Solutions, which was not very fun since both showed a form of the answer.

    TL;DR: The page stopped loading properly.

    • Milpotel 9 hours ago

      > Safari [..] The page stopped loading properly.

      Who would've guessed...

  • einpoklum 7 hours ago

    I tried to grep for "♫ piping ♫" at some point and the website got stuck. I wonder what it was trying to do...

    other than that - nice exercise for newbie shell dabblers :-)

  • dncornholio 9 hours ago

    Terrible. You cannot 'ls' if ls is not the right answer. Completely useless.

    • imp0cat 39 minutes ago

      That's not true. You can absolutely use ls and other commands to poke around before creating the winning command.