lnx1 1> mysum
1
2
8
10
^D
    21.00000000000000     
lnx1 2> mysum < first100
    5050.000000000000     

lnx1 3> mysum
12
2
8
a
10
b
^D
    32.00000000000000     
            2 invalid inputs

lnx1 4> mysum < first100 > mysum_result

lnx1 5> more !$
more mysum_result
    5050.000000000000