Bash randomizing variables

Question

I'm working on a bash script to basically play Rock Paper Scissors against the CPU. The problem I'm having is that I can't get it to randomly pick between variables, instead it just picks the first variable noted. Here is the section of code that needs work:

r="rock"
p="paper"
s="scissors"
RPS=$r||$p||$s    #The line that needs to be fixed
#rps=$r||$p||$s works but only outputs rock...
echo $RPS

I've tried looking for ways to do this on forums but google only pops up forums for randomly picking lines from another file and not within the file itself.

nosid · Accepted Answer · 2012-07-18 15:25:34Z

4

declare -a values=(rock paper scissors)
echo "${values[$(( $RANDOM % ${#values[*]} ))]}"

answered Jul 18, 2012 at 15:25

nosid

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4 Comments

Hai Vu Over a year ago

This solution is more throughout than mine for it does not hardcoded the size of the array (3).

xCra2yx Over a year ago

That worked pretty well...now I'm just having a problem with it deciding wins, loss, and draw -_- If I pick Rock no matter what the Cpu picks it's a draw. If I pick Paper I always win. If I pick Scissors the CPU always wins...

xCra2yx Over a year ago

Well I fixed that and everything is running great

Dennis Williamson Over a year ago

An array subscript is already an arithmetic context so $(()) isn't necessary.

Hai Vu · Accepted Answer · 2012-07-18 15:34:31Z

2

How about something like this:

choices=(rock paper cissors) # Define an array with 3 choices
RPS=${choices[$RANDOM%3]}    # Pick one at random

Discussion

Bash has a built-in variable called $RANDOM, which returns a random integer.

edited Jul 18, 2012 at 15:34

answered Jul 18, 2012 at 15:29

Hai Vu

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2 Comments

xCra2yx Over a year ago

I knew bash had a built-in random function (just like batch) but I couldn't figure how to use it in the manner I needed, but thanks now I know how to use it better!

xCra2yx Over a year ago

I ended up using this method and the program is running great!

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