postinst is in im 1:152-1.
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 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 | #! /bin/sh
set -e
. /usr/share/debconf/confmodule
db_get im/rpop
if [ "$RET" = "true" ]; then
  if [ ! type suidperl >/dev/null 2>&1 ]; then
    echo "The suidperl command is not found."
    db_purge
    exit 255
  else
    if dpkg-statoverride --list /usr/bin/imget >/dev/null ; then
      dpkg-statoverride --remove /usr/bin/imget
    fi
    dpkg-statoverride --update --add root root 4755 /usr/bin/imget
  fi
else
  if dpkg-statoverride --list /usr/bin/imget >/dev/null ; then
    dpkg-statoverride --remove /usr/bin/imget
  fi
  chmod 0755 /usr/bin/imget
fi
db_get im/siteconfig_by_hand
if [ "$RET" = "false" ]; then
  db_get im/fromdomain
  FROM_DOMAIN="$RET"
  db_get im/todomain
  TO_DOMAIN="$RET"
  db_get im/organization
  ORGANIZATION="$RET"
  db_get im/use_maildir
  if [ "$RET" = "true" ]; then
    MBOXSTYLE="qmail"
  else
    MBOXSTYLE=""
  fi
  TMPCONFIG=/etc/im/SiteConig.postinst-tmp
  cat <<POSTINST_EOF_OF_IM > $TMPCONFIG
FromDomain=$FROM_DOMAIN	# domain of your mail address
ToDomain=$TO_DOMAIN	# domain when domain part is omitted
Org=$ORGANIZATION	# for news posting
MBoxStyle=$MBOXSTYLE	# qmail or not
POSTINST_EOF_OF_IM
  if [ -f /etc/im/SiteConfig ]; then
    if cmp -s /etc/im/SiteConfig $TMPCONFIG ; then
      rm -f $TMPCONFIG
    else
      savelog /etc/im/SiteConfig
      rm -f /etc/im/SiteConfig
      mv $TMPCONFIG /etc/im/SiteConfig
    fi
  else
    mv $TMPCONFIG /etc/im/SiteConfig
  fi
fi
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