Bash Version of C64 Code Art: 10 PRINT CHR$(205.5+RND(1)); : GOTO 10

Question

I picked up a copy of the book 10 PRINT CHR$(205.5+RND(1)); : GOTO 10

• http://www.amazon.com/10-PRINT-CHR-205-5-RND/dp/0262018462

This book discusses the art produced by the single line of Commodore 64 BASIC:

10 PRINT CHR$(205.5+RND(1)); : GOTO 10

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This just repeatedly prints randomly character 205 or 206 to the screen from the PETSCII set:

• http://en.wikipedia.org/wiki/PETSCII
• https://vimeo.com/26472518

I'm not sure why the original uses the characters 205 and 206 instead of the identical 109 and 110. Also, I prefer to add a clear at the beginning. This is what I usually type into the C64:

1?CHR$(147)
2?CHR$(109.5+RND(1));:GOTO2
RUN

You can try this all for yourself in an emulator, such as this one using Flash or JavaScript:

• http://codeazur.com.br/stuff/fc64_final/

• http://www.kingsquare.nl/jsc64

  When inputting the above code into the emulators listed, you'll need to realize that

  • ( is *
  • ) is (
  • + is ]

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I decided it would be amusing to write a bash line to do something similar.

I currently have:

clear; while :; do [ $(($RANDOM%2)) -eq 0 ] && (printf "\\") || (printf "/"); done;

Two questions:

1. Any suggestions for making this more concise?
2. Any suggestions for a better output character? The forward and backward slash are not nearly as beautiful since their points don't line up. The characters used from PETSCII are special characters, not slashes. I didn't see anything in ASCII that could work as well, but maybe you can suggest a way to pull in a character from UTF-8 or something else?

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Best ANSWERS So Far

Shortest for bash (40 characters):

yes 'c=(╱ ╲);printf ${c[RANDOM%2]}'|bash

Here is a short one for zsh (53 characters):

c=(╱ ╲);clear;while :;do printf ${c[RANDOM%2+1]};done

Here is an alias I like to put in my .bashrc or .profile

alias art='c=(╱ ╲);while :;do printf "%s" ${c[RANDOM%2]};done'

Funny comparing this to the shortest I can do for C64 BASIC (23 characters):

1?C_(109.5+R_(1));:G_1

The underscores are shift+H, shift+N, and shift+O respectively. I can't paste the character here since they are specific to PETSCII. Also, the C64 output looks prettier ;)

You can read about the C64 BASIC abbreviations here:

• http://www.commodore.ca/manuals/c64_programmers_reference/c64-programmers_reference_guide-02-basic_language_vocabulary.pdf

Answer 1

After looking at some UTF stuff:

2571 BOX DRAWINGS LIGHT DIAGONAL UPPER RIGHT TO LOWER LEFT
2572 BOX DRAWINGS LIGHT DIAGONAL UPPER LEFT TO LOWER RIGHT

(╱‬ and ╲) seem best.

f="╱╲";while :;do print -n ${f[(RANDOM % 2) + 1]};done

also works in zsh (thanks Clint on OFTC for giving me bits of that)