Specify a specific output file. If not specified with `-o', then it's determined by puzzling over the input file's suffix (see the `-i <input-file>' option). When in doubt, it reverts to the standard output. You may also specify standard output as the "output file" with `-o -'.

(For hackers only.) If the first character to the `-o' argument is a `|', then the output is piped through the shell command(s) that presumably follow.