5.4. PRINTER, LPDEST, NPRINTER, and NGPRINTER Environment Variables

If no command line option is specified, the LPRng clients will use the first defined PRINTER, LPDEST, NPRINTER, or NGPRINTER environment variable value and will use the value as though specified as a -P$PRINTER command line literal. If the value has the form -Pprinter@host the print queue will be printer on server host and not consult the printcap database. If the value has the form printer then the printcap will be searched for a printer printcap entry. For example:

export PRINTER=laser@10.0.0.1; lpr
  equivalent to printcap entry:
    laser:lp=laser@10.0.0.1
export PRINTER=pr; lpr
  look up printcap entry for 'lp'