lnx1 1> tdvfrom
 usage: tdvfrom <file name>

        Use 'tdvfrom -' to read from standard input

lnx1 2> tdvfrom -
1
2
3
4
5
^D
 tdvfrom:            5 read from -

lnx1 3> tdvfrom first100
 tdvfrom:          100 read from first100