Q: How can I direct output to the printer?
A: Under Unix, either use popen (see question 19.30) to write to the lp or lpr program, or perhaps open a special file like /dev/lp. Under MS-DOS, write to the (nonstandard) predefined stdio stream stdprn, or open the special files PRN or LPT1. Under some circumstances, another (and perhaps the only) possibility is to use a window manager's screen-capture function, and print the resulting bitmap.
PCS Sec. 5.3 pp. 72-74