How to select a random item from an array in shell
ArraysShellRandomArrays Problem Overview
I'm creating a bot in Shell Script:
# Array with expressions
expressions=("Ploink Poink" "I Need Oil" "Some Bytes are Missing!" "Poink Poink" "Piiiip Beeeep!!" "Hello" "Whoops! I'm out of memmory!")
# Seed random generator
RANDOM=$$$(date +%s)
# Loop loop loop loop loop loop ...
while [ 1 ]
do
# Get random expression...
selectedexpression=${expressions[$RANDOM % ${#RANDOM[*]}]}
# Write to Shell
echo $selectedexpression
# Wait an half hour
sleep 1 # It's one second for debugging, dear SOers
done
I want that it prints a random item from the expressions
every second. I tried this but it does not work. It only prints the first one (Ploink Poink) every time. Can anyone help me out?
Thanks
Arrays Solutions
Solution 1 - Arrays
Change the line where you define selectedexpression
to
selectedexpression=${expressions[ $RANDOM % ${#expressions[@]} ]}
You want your index into expression
to be a random number from 0 to the length of the expression
array. This will do that.
Solution 2 - Arrays
arr[0]="Ploink Poink"
arr[1]="I Need Oil"
arr[2]="Some Bytes are Missing!"
arr[3]="Poink Poink"
arr[4]="Piiiip Beeeep!!"
arr[5]="Hello"
arr[6]="Whoops! I'm out of memmory!"
rand=$[$RANDOM % ${#arr[@]}]
echo $(date)
echo ${arr[$rand]}
Solution 3 - Arrays
Here's another solution that may be a bit more random than Jacob Mattison's solution (hard to say from the jot
manpages):
declare -a expressions=('Ploink' 'I Need Oil' 'Some Bytes are Missing' 'Poink Poink' 'Piiiip Beeeep' 'Hello' 'Whoops I am out of memory')
index=$( jot -r 1 0 $((${#expressions[@]} - 1)) )
selected_expression=${expressions[index]}
Solution 4 - Arrays
Solution using shuf:
expressions=("Ploink Poink" "I Need Oil" "Some Bytes are Missing!" "Poink Poink" "Piiiip Beeeep!!" "Hello" "Whoops! I'm out of memmory!")
selectedexpression=$(printf "%s\n" "${expressions[@]}" | shuf -n1)
echo $selectedexpression
Or probably better:
select_random() {
printf "%s\0" "$@" | shuf -z -n1 | tr -d '\0'
}
expressions=("Ploink Poink" "I Need Oil" "Some Bytes are Missing!" "Poink Poink" "Piiiip Beeeep!!" "Hello" "Whoops! I'm out of memmory!")
selectedexpression=$(select_random "${expressions[@]}")
echo "$selectedexpression"
Solution 5 - Arrays
for random
rand=("q" "w")
r=$(shuf -i 0-${#jndi[@]} -n 1)
echo ${rand[$r]}
2. echo $((1 + $RAND % 5))
// for number between 1..5