More Arithmetic

• You may also do arithmetic in array subscripts (arrays come later), so that these examples all have the same effect on declare -i x=3

• let x+=1
• let "x = x + 1"
• (( x += 1 ))
• echo $[ x = x + 1 ]
• echo $(( x += 1 ))
• array[x++]="value"

• In each case, echo $x will print the result 4