8 ms·

This was a small side project I completed recently, would love to hear feedback. Thanks!

by zoidb 10y ago

garettmd 10y ago
I was on the 3rd challenge, listing files in a directory, one per line, and it didn't accept "ls -l", but it did accept "ls"
- zoidb 10y ago
  Yeah it's particular about the output that it expects.
  - garettmd 10y ago
    I guess my point is that "ls" shouldn't be an answer. Typically it will print out multiple files on a line. If it's just checking for output and not the actual command someone entered, there should probably be more than one file in the directory to show that it will actually print one file per line.
    - zoidb 10y ago
      Because it is executed outside of a terminal (the execution isn't in javascript) you get a single column output. Probably would be better to be more specific in the descriptions, thanks for the suggestion.
    - zokier 10y ago
      The mostly correct answer is `ls -1`. Just mostly, because it falls to the classic unix trap (filenames can contain almost anything) which also shows that the challenge is ill defined. What is the expected result if the filename contains newlines? And this is not just some hypothetical scenario, just today at work I encountered a file with cursor movement terminal escape sequences in the filename.
      - lisivka 10y ago
        `ls -1b` should work correctly in your case. Option -b (or --escape) enables C-style escapes. IMHO, it should be on by default.
    - saghm 10y ago
      Although it often doesn't get printed like that, shells do consider the output of `ls` to be multiple lines. Try doing `ls > foo.txt` and looking at the output file (or more directly, `ls | wc -l`).
      - jjnoakes 10y ago
        That isn't the shell considering the output one per line. ls will change the way it writes its output if it detects that stdout is a tty versus a pipe or redirect.
  - JoshTriplett 10y ago
    It seems to accept any command that produces the expected output, though. That question should specifically say that it only wants the filenames, which would make it clear that `ls -l` doesn't produce the desired result.
- brennen 10y ago
  Same. Seems like the wording on some questions could use tweaking. Not bad overall, though.
  - notheguyouthink 10y ago
    If anything, i'd argue that it's incorrect. I first tried `ls -l`, then realized "oh, there could be hidden files so `-l` is not correct. Yet, `ls -la` failed too. To list "all files", you'd need to include hidden right? Well, to be sure, at least.
- tedmiston 10y ago
  I took this to mean it wanted only filenames and nothing else. I used: ls -1
JoshTriplett 10y ago
I really like this; reminiscent of the Python Challenge, but for shell. You should support bash's double-star wildcard, which works recursively. Several of the challenges that currently require find -name 'access.log*' -print0 | xargs -0 somecommand could just use somecommand **/access.log* instead. You might also encourage people to look up manpages. For instance, someone who doesn't know about "grep -h" may want to look at the manpage for grep. You could make "man grep" link to http://man7.org/linux/man-pages/man1/grep.1.html http://man7.org/linux/man-pages/man1/grep.1.html . Tab completion doesn't always include all files; for instance, it doesn't include split-me.txt Have you considered logging all unique successful solutions (filtering out minor whitespace differences) to each challenge? That would let people who have completed each challenge see other potential approaches to the problem, and perhaps learn about new commands.
- zokier 10y ago
  > You should support bash's double-star wildcard, which works recursively It depends on what the educational goals are, but alternatively OP could swing on the opposite direction and go with a very vanilla POSIX sh style shell (maybe dash) to discourage bashisms. I might of course be bit biased because `find` is one of my favorite utils (generally with -exec instead of -print0|xargs -0) and I practically never use newfangled doublestar globbing
  - JoshTriplett 10y ago
    Teaching efficient bash usage and teaching portable shell scripting seem related but distinct. This challenge specifically mentions that it uses bash.
    - zokier 10y ago
      Yes sure, I wasn't trying to say that going full bash is a bad thing. I was merely presenting an alternative.
- zoidb 10y ago
  Ah good point, the commands are run in a bash 4 subshell actually but by default the globstar option is off.
JoshTriplett 10y ago
Have you considered running the commands directly in JavaScript, rather than via AWS? With some work, you could run everything inside emscripten in the browser, and then you don't need to worry about security, sandboxing, or scaling.
- zoidb 10y ago
  Yeah though this was pretty easy to setup and I was looking to replicate an authentic command line experience including the standard unix utilities.
- akavel 10y ago
  In this case you'd probably be better "just" going for http://stackoverflow.com/questions/6030407/how-does-linux-emulator-in-javascript-by-fabrice-bellard-work http://stackoverflow.com/questions/6030407/how-does-linux-em... ?
coherentpony 10y ago
grep -rl 500 . wasn't accepted. Am I wrong or is it wrong?
- leblancfg 10y ago
  You are: grep matches strings, not integers. grep -rl '500' works just fine.
  - tne 10y ago
    There is no concept of an integer on an argument vector. Quoting in bash just escapes IFS characters (usually whitespace) to control whether to include them in a given argument on the vector, but these arguments (as passed to exec) are always character strings (with or without quoting).
  - godelski 10y ago
    Interestingly enough grep -rl "500" . doesn't work because it returns with the "./".
- snuxoll 10y ago
  Only filenames matching access.log should be returned. Unfortunately, since shopt globstar is disabled I ended up needing to do this: grep 500 $(find . -type f -iname "access.log*")
  - JoshTriplett 10y ago
    You could also include "shopt -s globstar; " at the beginning of your line.
  - joshka 10y ago
    grep -r 500 --include access.log
- slavik81 10y ago
  That returns the filenames in the format "./access.log" but it wanted "access.log". It's a bug. I used echo -e 'access.log\naccess.log.1\nREADME'. :D
meggar 10y ago
I tried "rm -rf". Not sure if it worked.
- ianmcgowan 10y ago
  I got stuck on this one too. Strangely "find . -delete" worked fine. I'm getting Internal Server Error" now, so perhaps a victim of it's own popularity?
wichert 10y ago
It looks a bit like the cwd is shared between multiple users accessing the site? I suddenly got errors that access.log disappears, after which my pwd seemed to randomly change.
- zoidb 10y ago
  Nothing is shared in fact every time you submit a command you get a new subshell in a new container. If it is reproducible I will track down the problem.
akavel 10y ago
The finale was weird for me, kinda anticlimactic (back to "hello world"); is that how it's expected to behave? No "finished" message or something? Or is my NoScript interfering somehow? She is betraying us! Russia alone must save Europe. Our gracious sovereign recognizes his high vocation and will be true to it. That is the one thing I have faith in! Our good and wonderful sovereign has to perform the noblest role on earth, and he is so virtuous and noble that God will not forsake him. He will fulfill his vocation and crush the hydra of revolution, which has become more terrible than ever in the person of this murderer and villain! # Correct! # You have a new challenge! # Print "hello world". # Hint: There are many ways to print text on # the command line, one way is with the 'echo' # command. # # Try it below and good luck! # bash(0)> printf "hello world" hello world # Correct! bash(0)>
- mnemotronic 10y ago
  # Print "hello world". # Hint: There are many ways to print text on # the command line, one way is with the 'echo' # command. # # Try it below and good luck! # bash(0)> echo '"hello world".' "hello world". bash(0)> What is this, Android? Sheesh.
- schoen 10y ago
  Nach dem Spiel ist vor dem Spiel? https://en.wikipedia.org/wiki/Sepp_Herberger#References_in_popular_culture https://en.wikipedia.org/wiki/Sepp_Herberger#References_in_p... (I would also like it if the site somehow indicated that you got to the end or congratulated you on finishing everything.)
  - zoidb 10y ago
    I honestly didn't think anyone would complete all of them :) I'll put something cool at the end, thanks for the suggestion.
inetknght 10y ago
After completing the challenges (only had to lookup references on bash parameter expansion and how to read lines without parsing them), I would say that it might be helpful to have some reference information available whether via clicking to a third party URL. It'd also be _really_ nifty to be able to compare my solutions against others' solutions.
ianmcgowan 10y ago
Super-cool! Some pieces of feedback: 1) It would be nice to have something special happen when you solve all the puzzles, rather than going back to the first. Some javascript balloons dropping from the ceiling? ;_) 2) Some of the problems, it's hard to tell why an answer doesn't work. A side-by-side diff showing my results compared to the expected results might help? 3) After solving (perhaps just one, or maybe all), I'd love to see other people's solutions. That'd be quite educational.
wlib 10y ago
I'm making something related as a side project too, and the major problem I have right now is showing a terminal on the page. As you can see I'm relying on archaic methods... https://term.surge.sh https://term.surge.sh
johnloeber 10y ago
Fun! Needs tab-complete.
cglouch 10y ago
I really enjoyed this, it was a nice way to practice/learn some command line tricks. In particular I got better acquainted with the find command. Nice work! My only suggestion would be to have an option to show a solution (yours or perhaps even a user-submitted one) if you get stuck on a particular challenge.

This was a small side project I completed recently, would love to hear feedback. Thanks!

by zoidb 10y ago

This was a small side project I completed recently, would love to hear feedback. Thanks!

I was on the 3rd challenge, listing files in a directory, one per line, and it didn't accept "ls -l", but it did accept "ls"

zoidb 10y ago
Yeah it's particular about the output that it expects.
- garettmd 10y ago
  I guess my point is that "ls" shouldn't be an answer. Typically it will print out multiple files on a line. If it's just checking for output and not the actual command someone entered, there should probably be more than one file in the directory to show that it will actually print one file per line.
  - zoidb 10y ago
    Because it is executed outside of a terminal (the execution isn't in javascript) you get a single column output. Probably would be better to be more specific in the descriptions, thanks for the suggestion.
  - zokier 10y ago
    The mostly correct answer is `ls -1`. Just mostly, because it falls to the classic unix trap (filenames can contain almost anything) which also shows that the challenge is ill defined. What is the expected result if the filename contains newlines? And this is not just some hypothetical scenario, just today at work I encountered a file with cursor movement terminal escape sequences in the filename.
    - lisivka 10y ago
      `ls -1b` should work correctly in your case. Option -b (or --escape) enables C-style escapes. IMHO, it should be on by default.
  - saghm 10y ago
    Although it often doesn't get printed like that, shells do consider the output of `ls` to be multiple lines. Try doing `ls > foo.txt` and looking at the output file (or more directly, `ls | wc -l`).
    - jjnoakes 10y ago
      That isn't the shell considering the output one per line. ls will change the way it writes its output if it detects that stdout is a tty versus a pipe or redirect.
- JoshTriplett 10y ago
  It seems to accept any command that produces the expected output, though. That question should specifically say that it only wants the filenames, which would make it clear that `ls -l` doesn't produce the desired result.
brennen 10y ago
Same. Seems like the wording on some questions could use tweaking. Not bad overall, though.
- notheguyouthink 10y ago
  If anything, i'd argue that it's incorrect. I first tried `ls -l`, then realized "oh, there could be hidden files so `-l` is not correct. Yet, `ls -la` failed too. To list "all files", you'd need to include hidden right? Well, to be sure, at least.
tedmiston 10y ago
I took this to mean it wanted only filenames and nothing else. I used: ls -1

JoshTriplett 10y ago

I really like this; reminiscent of the Python Challenge, but for shell. You should support bash's double-star wildcard, which works recursively. Several of the challenges that currently require find -name 'access.log*' -print0 | xargs -0 somecommand could just use somecommand **/access.log* instead. You might also encourage people to look up manpages. For instance, someone who doesn't know about "grep -h" may want to look at the manpage for grep. You could make "man grep" link to http://man7.org/linux/man-pages/man1/grep.1.html http://man7.org/linux/man-pages/man1/grep.1.html . Tab completion doesn't always include all files; for instance, it doesn't include split-me.txt Have you considered logging all unique successful solutions (filtering out minor whitespace differences) to each challenge? That would let people who have completed each challenge see other potential approaches to the problem, and perhaps learn about new commands.

zokier 10y ago
> You should support bash's double-star wildcard, which works recursively It depends on what the educational goals are, but alternatively OP could swing on the opposite direction and go with a very vanilla POSIX sh style shell (maybe dash) to discourage bashisms. I might of course be bit biased because `find` is one of my favorite utils (generally with -exec instead of -print0|xargs -0) and I practically never use newfangled doublestar globbing
- JoshTriplett 10y ago
  Teaching efficient bash usage and teaching portable shell scripting seem related but distinct. This challenge specifically mentions that it uses bash.
  - zokier 10y ago
    Yes sure, I wasn't trying to say that going full bash is a bad thing. I was merely presenting an alternative.
zoidb 10y ago
Ah good point, the commands are run in a bash 4 subshell actually but by default the globstar option is off.

JoshTriplett 10y ago

Have you considered running the commands directly in JavaScript, rather than via AWS? With some work, you could run everything inside emscripten in the browser, and then you don't need to worry about security, sandboxing, or scaling.

zoidb 10y ago
Yeah though this was pretty easy to setup and I was looking to replicate an authentic command line experience including the standard unix utilities.
akavel 10y ago
In this case you'd probably be better "just" going for http://stackoverflow.com/questions/6030407/how-does-linux-emulator-in-javascript-by-fabrice-bellard-work http://stackoverflow.com/questions/6030407/how-does-linux-em... ?

coherentpony 10y ago

grep -rl 500 . wasn't accepted. Am I wrong or is it wrong?

leblancfg 10y ago
You are: grep matches strings, not integers. grep -rl '500' works just fine.
- tne 10y ago
  There is no concept of an integer on an argument vector. Quoting in bash just escapes IFS characters (usually whitespace) to control whether to include them in a given argument on the vector, but these arguments (as passed to exec) are always character strings (with or without quoting).
- godelski 10y ago
  Interestingly enough grep -rl "500" . doesn't work because it returns with the "./".
snuxoll 10y ago
Only filenames matching access.log should be returned. Unfortunately, since shopt globstar is disabled I ended up needing to do this: grep 500 $(find . -type f -iname "access.log*")
- JoshTriplett 10y ago
  You could also include "shopt -s globstar; " at the beginning of your line.
- joshka 10y ago
  grep -r 500 --include access.log
slavik81 10y ago
That returns the filenames in the format "./access.log" but it wanted "access.log". It's a bug. I used echo -e 'access.log\naccess.log.1\nREADME'. :D

meggar 10y ago

I tried "rm -rf". Not sure if it worked.

ianmcgowan 10y ago
I got stuck on this one too. Strangely "find . -delete" worked fine. I'm getting Internal Server Error" now, so perhaps a victim of it's own popularity?

wichert 10y ago

It looks a bit like the cwd is shared between multiple users accessing the site? I suddenly got errors that access.log disappears, after which my pwd seemed to randomly change.

zoidb 10y ago
Nothing is shared in fact every time you submit a command you get a new subshell in a new container. If it is reproducible I will track down the problem.

akavel 10y ago

The finale was weird for me, kinda anticlimactic (back to "hello world"); is that how it's expected to behave? No "finished" message or something? Or is my NoScript interfering somehow? She is betraying us! Russia alone must save Europe. Our gracious sovereign recognizes his high vocation and will be true to it. That is the one thing I have faith in! Our good and wonderful sovereign has to perform the noblest role on earth, and he is so virtuous and noble that God will not forsake him. He will fulfill his vocation and crush the hydra of revolution, which has become more terrible than ever in the person of this murderer and villain! # Correct! # You have a new challenge! # Print "hello world". # Hint: There are many ways to print text on # the command line, one way is with the 'echo' # command. # # Try it below and good luck! # bash(0)> printf "hello world" hello world # Correct! bash(0)>

mnemotronic 10y ago
# Print "hello world". # Hint: There are many ways to print text on # the command line, one way is with the 'echo' # command. # # Try it below and good luck! # bash(0)> echo '"hello world".' "hello world". bash(0)> What is this, Android? Sheesh.
schoen 10y ago
Nach dem Spiel ist vor dem Spiel? https://en.wikipedia.org/wiki/Sepp_Herberger#References_in_popular_culture https://en.wikipedia.org/wiki/Sepp_Herberger#References_in_p... (I would also like it if the site somehow indicated that you got to the end or congratulated you on finishing everything.)
- zoidb 10y ago
  I honestly didn't think anyone would complete all of them :) I'll put something cool at the end, thanks for the suggestion.

inetknght 10y ago

After completing the challenges (only had to lookup references on bash parameter expansion and how to read lines without parsing them), I would say that it might be helpful to have some reference information available whether via clicking to a third party URL. It'd also be _really_ nifty to be able to compare my solutions against others' solutions.

ianmcgowan 10y ago

Super-cool! Some pieces of feedback: 1) It would be nice to have something special happen when you solve all the puzzles, rather than going back to the first. Some javascript balloons dropping from the ceiling? ;_) 2) Some of the problems, it's hard to tell why an answer doesn't work. A side-by-side diff showing my results compared to the expected results might help? 3) After solving (perhaps just one, or maybe all), I'd love to see other people's solutions. That'd be quite educational.

wlib 10y ago

I'm making something related as a side project too, and the major problem I have right now is showing a terminal on the page. As you can see I'm relying on archaic methods... https://term.surge.sh https://term.surge.sh

johnloeber 10y ago

Fun! Needs tab-complete.

cglouch 10y ago

I really enjoyed this, it was a nice way to practice/learn some command line tricks. In particular I got better acquainted with the find command. Nice work! My only suggestion would be to have an option to show a solution (yours or perhaps even a user-submitted one) if you get stuck on a particular challenge.