Bash Arrays

arr=() # empty array
arr=(val1 val2 val3) # initialize with values
arr[0]=value # assign element

${arr[0]} # first element
${arr[-1]} # last element
${arr[@]} # all elements
${arr[*]} # all elements as string

${#arr[@]} # number of elements
${#arr[0]} # length of first element

${arr[@]:2:3} # 3 elements starting from index 2

arr+=(val) # append element
arr=(${arr[@]} val) # append element (alt)

unset arr[1] # remove element at index 1
unset arr # remove entire array

for item in ${arr[@]}; do
  echo $item
done

# With index:
for i in ${!arr[@]}; do
  echo ${arr[$i]}
done