/usr/share/doc/printer-driver-pnm2ppa/examples/sample_scripts/lprbw is in printer-driver-pnm2ppa 1.13+nondbs-0ubuntu6.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 | #!/bin/sh
cat $1 | \
gs -sDEVICE=pbmraw -q -sPAPERSIZE=a4 -dNOPAUSE -r600 -sOutputFile=- - | \
pnm2ppa --bw --eco $2 $3 $4 $5 -i - -o /dev/lp0
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