@

@ variable = expression
@ variable [ n ] = expression
@

Assign the value of the arithmetic expression to variable , or to the n th element of variable if the index n is specified. With no variable or expression specified, print the values of all shell variables (same as set ). Expression operators as well as examples are listed in the earlier section "Expressions." Two special forms are also valid:

@ variable ++

Increment variable by one.

@ variable --

Decrement variable by one.