Compatibility
CUPS provides both the System V and Berkeley printing commands, so users can continue with traditional commands for printing via CUPS. CUPS uses port 631 (TCP and UDP), which is the standard IPP port, and optionally on port 515 by inetd, launchd, the Solaris Service Management Facility, or xinetd which use the cups-lpd helper program to support LPD printing. When CUPS is installed the lp System V printing system command and the lpr Berkeley printing system commands are installed as compatible programs. This allows a standard interface to CUPS and allows maximum compatibility with existing applications that rely on these printing systems.
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