Added a rainbow screensaver script

This script displays a colorful rainbow animation in the terminal. It has an option to list the rainbow instead of animating it using the command: rainbow -l.

Author: IgnasFalcon

rainbow.sh

@@ -0,0 +1,63 @@
+#!/bin/bash
+
+#Credit to IgnasFalcon for this script
+#https://github.com/IgnasFalcon/Rainbow-Shell
+#Usage: rainbow [-l] [CYCLES]
+
+clear
+
+#Define list option
+list_mode=false
+
+while getopts "l" opt; do
+    case "$opt" in
+        l) list_mode=true ;;
+        *) exit 1 ;;
+    esac
+done
+
+#This removes the -l
+shift $((OPTIND - 1))
+
+#Define colors
+colors=(
+  "\e[31m"
+  "\e[38;5;208m"
+  "\e[33m" # Replacement for yellow
+  "\e[32m"
+  "\e[36m"
+  "\e[34m" # Closest to indigo
+  "\e[35m"
+)
+
+#Rainbow function
+rainbow() {
+    for c in "${colors[@]}"; do
+        if ! $list_mode; then
+            clear
+        fi
+        echo -e "${c}$(echo "
+ooooooooo.         .o.       ooooo ooooo      ooo oooooooooo.    .oooooo.   oooooo   oooooo     oooo 
+.888   .Y88.      .888.      .888. .888b.     .8. .888.   .Y8b  d8P.  .Y8b   .888.    .888.     .8.  
+ 888   .d88.     .88888.      888   8 .88b.    8   888     888 888      888   .888.   .8888.   .8.   
+ 888ooo88P.     .8. .888.     888   8   .88b.  8   888oooo888. 888      888    .888  .8..888. .8.    
+ 888.88b.      .88ooo8888.    888   8     .88b.8   888    .88b 888      888     .888.8.  .888.8.     
+ 888  .88b.   .8.     .888.   888   8       .888   888    .88P .88b    d88.      .888.    .888.      
+o888o  o888o o88o     o8888o o888o o8o        .8  o888bood8P.   .Y8bood8P.        .8.      .8.")\e[0m\r"
+        sleep 1
+    done
+}
+
+#Display rainbow
+index=$(( $1 + 0 ))
+if [[ $1 > "" ]]; then
+    while [[ $index > 0 ]]; do
+        rainbow
+        (( index-- ))
+    done
+else
+  while true; do
+      rainbow
+      (( index-- ))
+  done
+fi