The lpr command is a legacy program provided by CUPS for sending files to the printer queues on the command line. It is one of the Berkeley (lpr) printing commands that CUPS supports for compatibility with other Unix-like systems. The lpr command accepts one or more filenames as arguments and sends them to the default or specified printer. It also supports several options to control the printing process, such as the number of copies, the page size, the orientation, and the priority. The lpr command is equivalent to the lp command, which is one of the System V (lp) printing commands that CUPS also supports. However, the lp command has more options and features than the lpr command, and is recommended for use with CUPS. Reference:
Command-Line Printing and Options - CUPS
Command-Line Printer Administration - CUPS
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