After invoking garead the user is prompted with
Name for output file:To proceed, the user types the path name of a satellite file followed by return. The program then reads characters from the standard input and writes the characters to the output file, filtering out carriage returns. garead terminates when it receives a CTRL-D.
If 5120 or fewer characters will be read from the GA, the user need not create the output file in advance. If more than 5120 characters are expected, the user must create the output file in advance, specifying the expected block size.