postinst is in dovecot-core 1:2.0.19-0ubuntu2.1.
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 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164  | #!/bin/sh
set -e
if [ "$1" = "configure" ]; then
  CONFFILES="dovecot.conf \
    dovecot-db.conf.ext \
    dovecot-dict-sql.conf.ext \
    dovecot-sql.conf.ext \
    conf.d/10-auth.conf \
    conf.d/10-director.conf \
    conf.d/10-logging.conf \
    conf.d/10-mail.conf \
    conf.d/10-master.conf \
    conf.d/10-ssl.conf \
    conf.d/15-lda.conf \
    conf.d/90-acl.conf \
    conf.d/90-plugin.conf \
    conf.d/90-quota.conf \
    conf.d/auth-deny.conf.ext \
    conf.d/auth-master.conf.ext \
    conf.d/auth-passwdfile.conf.ext \
    conf.d/auth-static.conf.ext \
    conf.d/auth-system.conf.ext \
    conf.d/auth-vpopmail.conf.ext"
  OLD_CONFFILES="dovecot-ldap.conf \
    dovecot-sql.conf \
    protocols.conf \
    dovecot-ldap.conf.ext \
    conf.d/20-imap.conf \
    conf.d/20-lmtp.conf \
    conf.d/20-managesieve.conf \
    conf.d/20-pop3.conf \
    conf.d/90-sieve.conf \
    conf.d/auth-ldap.conf.ext"
    OLD_DPKG_CONFFILES="/etc/cron.daily/dovecot \
      /etc/dovecot/dovecot-dict-sql-example.conf \
      /etc/dovecot/dovecot-db-example.conf"
    # purge old dpkg handled conffiles (we can't use dpkg-maintscript-helper because package rename)
    for conffile in $OLD_DPKG_CONFFILES ; do
      [ -e "$conffile" ] || continue
      confmd5="$(md5sum $conffile | awk '{print $1}')"
      dpkgmd5="$(dpkg-query -W -f='${Conffiles}' $PKGNAME | sed -n -e "\' $conffile ' { s/ obsolete$//; s/.* //; p }")"
      if [ "$confmd5" != "$dpkgmd5" ]; then
        echo "Obsolete conffile $conffile has been modified by you."
        echo "Saving as $conffile.dpkg-bak ..."
        mv -f "$conffile" "$conffile".dpkg-bak
      else
        echo "Removing obsolete conffile $conffile ..."
        rm -f "$conffile"
      fi
    done
  # purge old ucf handled conffiles
  for conffile in $OLD_CONFFILES ; do
    if ucfq "/etc/dovecot/${conffile}" --with-colons | grep -q "^/etc/dovecot/${conffile}:dovecot-common:"; then
      if ucfq --with-colons "/etc/dovecot/${conffile}" | grep -q ":Yes:No"; then
        rm -f "/etc/dovecot/${conffile}"
      fi
      ucf --purge /etc/dovecot/$conffile
      ucfr --purge dovecot-common /etc/dovecot/$conffile
      for ext in '~' '%' .bak .dpkg-tmp .dpkg-new .dpkg-old .dpkg-dist .ucf-new .ucf-old .ucf-dist;  do
        rm -f /etc/dovecot/$conffile$ext
      done
    fi
  done
  # if we are upgrading from dovecot-common take the ownership of configuration files
  for conffile in $(ucfq dovecot-common --with-colons | cut -f 1 -d :); do
    ucfr --force dovecot-core $conffile
    if [ "$conffile" = "/etc/dovecot/dovecot.conf" ]; then
      # avoid ucf question if the only difference is at the "protocols" line
      confmd5=$(sed 's/^protocols.*/protocols = none/' "$conffile" | md5sum | awk '{print $1}')
      ucfmd5=$(cat /var/lib/ucf/hashfile | grep "$conffile" | awk '{print $1}')
      if [ "$confmd5" = "$ucfmd5" ]; then
        sed -i 's/^protocols.*/protocols = none/' "$conffile"
      fi
      # remove old configuration bakup generated by postinst
      rm -f $conffile.bak
    fi
  done
  ## Users
  #
  if [ -z "`id -u dovecot 2> /dev/null`" ]; then
    adduser --system --group --home /usr/lib/dovecot --gecos "Dovecot mail server" \
            --no-create-home --disabled-password --quiet dovecot || true
  fi
  if [ -z "`id -u dovenull 2> /dev/null`" ]; then
    adduser --system --home /nonexistent --no-create-home --gecos "Dovecot login user" \
            --disabled-password --quiet dovenull || true
  fi
  for conffile in $CONFFILES ; do
    # Tell ucf that the file in /usr/share/dovecot is the latest
    # maintainer version, and let it handle how to manage the real
    # configuration file in /etc/dovecot.
    ucf --three-way /usr/share/dovecot/$conffile /etc/dovecot/$conffile
    ucfr dovecot-core /etc/dovecot/$conffile
    if [ "$conffile" != "dovecot.conf" ] && [ -f "/etc/dovecot/$conffile" ] &&
		[ `echo $conffile | cut -b -7` != "conf.d/" ]; then
      chmod 0640 /etc/dovecot/$conffile
      chgrp dovecot /etc/dovecot/$conffile
    fi
  done
  if [ -n "`id -u imapd 2> /dev/null`" ]; then
    deluser imapd || true
    delgroup imapd || true
  fi
  ## SSL Certs
  # Certs and key file
  SSL_CERT=$( (grep -m 1 "ssl_cert_file" /etc/dovecot/conf.d/10-ssl.conf  || echo '/etc/ssl/certs/dovecot.pem') | cut -d'=' -f2)
  SSL_KEY=$( (grep -m 1 "ssl_key_file" /etc/dovecot/conf.d/10-ssl.conf || echo '/etc/ssl/private/dovecot.pem') | cut -d'=' -f2)
  # Generate new certs if needed
  if [ -e $SSL_CERT ] && [ -e $SSL_KEY ]; then
    echo "You already have ssl certs for dovecot."
  else
    echo "Creating generic self-signed certificate: $SSL_CERT"
    echo "This certificate will expire in a year."
    echo "(replace with hand-crafted or authorized one if needed)."
    cd /etc/ssl/certs
    PATH=$PATH:/usr/bin/ssl
    if ! FQDN="$(hostname -f)"; then
        FQDN="$(hostname)"
        echo WARNING: Could not get FQDN, using \"$FQDN\".
    fi
    MAILNAME="$(cat /etc/mailname 2> /dev/null || echo "$FQDN")"
    (openssl req -newkey rsa:2048  -x509 -days 3652.5 -nodes \
	-rand /dev/urandom -out $SSL_CERT -keyout $SSL_KEY > /dev/null 2>&1 <<+
.
.
.
Dovecot mail server
$FQDN
$FQDN
root@$MAILNAME
+
    ) || echo "Warning : Bad SSL config, can't generate certificate."
  fi
  ucfr dovecot-core $SSL_CERT
  ucfr dovecot-core $SSL_KEY
  if [ ! -h $SSL_CERT ] && [ ! -h $SSL_KEY ]; then
    chown root:dovecot $SSL_CERT || true
    chmod 0644 $SSL_CERT || true
    chown root:dovecot $SSL_KEY || true
    chmod 0600 $SSL_KEY || true
  fi
fi
# Automatically added by dh_installinit
if [ -e "/etc/init/dovecot.conf" ]; then
	invoke-rc.d dovecot start || exit $?
fi
# End automatically added section
 |