preinst is in quagga-core 1.2.4-1.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | #!/bin/bash
set -eu
# create quaggavty group
addgroup --system quaggavty > /dev/null
# create quagga group
addgroup --system quagga > /dev/null
# create quagga user
adduser \
  --system \
  --ingroup quagga \
  --home /run/quagga/ \
  --no-create-home \
  --gecos "Quagga routing suite" \
  quagga  > /dev/null
# add quagga user to the quaggavty group
adduser quagga quaggavty
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