bittorf / shell_snake

portable posix shell snake game without bashisms

shell_snake in 574 chars (without shebang)

portable posix shell snake game without bashisms, inspired by http://codegolf.stackexchange.com/questions/4480/recreate-a-snake-game-in-a-console-terminal

coded during http://2014.revision-party.net/

I tried to be POSIX compliant (being as much portable as possible and avoid bashisms, even the random-number-generator does not need /proc). You can e.g. play it (using keys WASD) in your native terminal or via a SSH-session. There is also an unuglyfied/readable variant.

Some notes: shell-scripting is not suited for coding games 8-)

• to be fair, we only used so called 'builtins', which means:
  • no external calls of programs like 'clear', 'stty' or 'tput'
  • because of that, we redraw the whole screen on every move
  • the only used builtins (aka native commands) are:
    • echo, eval, while-loop, let, break, true, read, case, test, set, shift, alias, source
• there is no random number generator (PRNG), so we have to built our own
• getting a keystroke blocks, so we have to spawn another thread
  • for getting the event in parent-task we use a tempfile (ugly!)
• the snake itself is a list, which is cheap:
  • each element is a (x,y)-tuple
  • loosing the tail means: shift the list by 1
  • adding a (new) head means: append a string
• the grid is internally an array, but shell/sh does not know this:
  • we "emulated" array(x,y) via an ugly eval-call with global vars
• and finally: we had a lot of fun!

TODO for POSIX:

• rewrite 'while let $expression' calls (i like the endcondition)
• replace 'echo' with 'printf', e.g.: printf "\033[H"
• find a workaround for 'read -n'
• better kill 2nd thread at gameend