'How to select a random item from an array in shell

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

arraysshellrandom


Solution 1:[1]

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 2:[2]

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 3:[3]

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 4:[4]

for random

1.

rand=("q" "w") 
r=$(shuf -i 0-${#jndi[@]} -n 1)
echo ${rand[$r]}
  1. echo $((1 + $RAND % 5)) // for number between 1..5

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Mohsen Abasi
Solution 2 Powers
Solution 3
Solution 4 Netwons

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