preinst is in voms-clients 2.0.12-4build1.
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 | #!/bin/sh
set -e
for c in voms-proxy-init voms-proxy-info voms-proxy-destroy; do
  if [ -r /usr/bin/$c -a ! -h /usr/bin/$c ]; then
    rm -f /usr/bin/$c
  fi
  if [ -r /usr/share/man/man1/$c.1.gz -a ! -h /usr/share/man/man1/$c.1.gz ]; then
    rm -f /usr/share/man/man1/$c.1.gz
  fi
done
 |