diff --git a/tools/config.sh b/tools/config.sh
index 25d953163..038c61b20 100644
--- a/tools/config.sh
+++ b/tools/config.sh
@@ -4,7 +4,7 @@ debian_version=$(cat /etc/debian_version)
 debian_version=${debian_version%%.*}
 
 die() {
-  echo 
+  echo
   echo "Erreur: $1"
   echo
   exit 1
@@ -17,8 +17,8 @@ export PATH="${PATH}":/usr/sbin:/sbin
 umask 0022
 
 export SCODOC_DIR=/opt/scodoc
-export SCODOC_VAR_DIR=/opt/scodoc-data 
-
+export SCODOC_VAR_DIR=/opt/scodoc-data
+export SCODOC_INSTALL_STATUS_FILE="${SCODOC_VAR_DIR}/.install_status"
 export SCODOC_VERSION_DIR="${SCODOC_VAR_DIR}/config/version"
 export SCODOC_LOGOS_DIR="${SCODOC_VAR_DIR}/config/logos"
 
@@ -49,7 +49,7 @@ else
 fi
 export PSQL
 
-# tcp port for SQL server 
+# tcp port for SQL server
 # Important note: if changed, you should probably also change it in
 #      sco_utils.py (SCO_DEFAULT_SQL_PORT).
 export POSTGRES_PORT=5432
diff --git a/tools/debian/postinst b/tools/debian/postinst
index 9cae57ffd..26a550d52 100755
--- a/tools/debian/postinst
+++ b/tools/debian/postinst
@@ -3,11 +3,17 @@
 # Post-installation de scodoc
 # ici, le répertoire /opt/scodoc vient d'être installé
 
+set -euo pipefail
+
 cd /opt/scodoc || (echo "Error chdir to /opt/scodoc"; exit 1)
 
 # On peut donc charger la config:
-source /opt/scodoc/tools/config.sh
-source /opt/scodoc/tools/utils.sh
+source /opt/scodoc/tools/config.sh || (echo "Error loading /opt/scodoc/tools/config.sh"; exit 1)
+source /opt/scodoc/tools/utils.sh  || (echo "Error loading /opt/scodoc/tools/utils.sh"; exit 1)
+
+# Enleve fichier de statut d'installation s'il existe
+# (la présence de ce fichier indique que l'install s'est bien passée)
+remove_install_status
 
 # -- Création au besoin de notre utilisateur
 # adduser --system "${SCODOC_USER}"
@@ -26,7 +32,7 @@ do
     then
         echo adding $locname
         echo "$locname ${locname##*.}" >> /etc/locale.gen
-        /usr/sbin/locale-gen --keep-existing 
+        /usr/sbin/locale-gen --keep-existing
     fi
 done
 echo "debian postinst: scodoc9 systemd service is $(systemctl is-active scodoc9)"
@@ -44,7 +50,7 @@ then
     if [[ ! "${SN}" =~ ^[0-9].* ]]
     then
         SN='' # fix for invalid previous replies
-    fi 
+    fi
 else
     # first install
     echo "mode: install"
@@ -56,10 +62,10 @@ CMD="curl --fail --connect-timeout 5 --silent https://scodoc.org/scodoc-installm
 
 SVERSION="$(${CMD})"
 if [ "$?" == 0 ]; then
-  #echo "answer=${SVERSION}" 
+  #echo "answer=${SVERSION}"
   echo "${SVERSION}" > "${SCODOC_VERSION_DIR}"/scodoc.sn
 else
-  echo 'Warning: cannot connect to scodoc release server'  
+  echo 'Warning: cannot connect to scodoc release server'
 fi
 
 # ------------ LIEN VERS .env
@@ -117,7 +123,7 @@ cp "$SCODOC_DIR"/tools/etc/scodoc-logrotate /etc/logrotate.d/scodoc
 chmod 644 /etc/logrotate.d/scodoc
 
 # ------------ CONFIG SERVICE SCODOC
-echo 
+echo
 echo "Installation du service systemd scodoc9..."
 cp "$SCODOC_DIR"/tools/etc/scodoc9.service /etc/systemd/system/
 systemctl daemon-reload
@@ -134,3 +140,6 @@ systemctl enable scodoc9
 
 # --- RESTART SCODOC
 systemctl restart scodoc9
+
+# On est arrivé au bout du post-install !
+create_install_status
diff --git a/tools/debian/prerm b/tools/debian/prerm
new file mode 100644
index 000000000..eb5957e01
--- /dev/null
+++ b/tools/debian/prerm
@@ -0,0 +1,19 @@
+#!/bin/bash
+
+set -euo pipefail
+
+# Pre-removal script for scodoc
+# This script is called by dpkg before removing the package
+
+cd /opt/scodoc || (echo "Error chdir to /opt/scodoc"; exit 1)
+
+# On peut donc charger la config:
+source /opt/scodoc/tools/config.sh || (echo "Error loading /opt/scodoc/tools/config.sh"; exit 1)
+source /opt/scodoc/tools/utils.sh  || (echo "Error loading /opt/scodoc/tools/utils.sh"; exit 1)
+
+check_uid_root
+
+remove_install_status
+
+
+
diff --git a/tools/upgrade.sh b/tools/upgrade.sh
index 551ca1a88..93a5de317 100755
--- a/tools/upgrade.sh
+++ b/tools/upgrade.sh
@@ -1,15 +1,16 @@
 #!/bin/bash
 
 # Upgrade ScoDoc installation using APT
-#   
+#
 # This script STOP and RESTART ScoDoc and should be runned as root
 #
 # Upgrade also the Linux system using apt.
 #
-# Script for ScoDoc 9
+# Script for ScoDoc 9. Lancé automatiquement par scodoc-updater.
 #
 # E. Viennet, sep 2013, mar 2017, jun 2019, aug 2020, dec 2020, aug 21
 
+set -euo pipefail
 
 # Le répertoire de ce script:
 SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
@@ -29,7 +30,7 @@ if [ -z "$SCODOC_UPGRADE_RUNNING" ]
        # install spécifiquement scodoc9, utile si les dépendances Debian de scodoc9
        # ont été changées, ce qui peut provoquer un
        # "packages have been kept back"
-       apt install scodoc9
+       apt install scodoc9 || alarm_admin "apt install scodoc9 failed"
 fi
 systemctl restart redis
 systemctl restart nginx
diff --git a/tools/utils.sh b/tools/utils.sh
index e751501a4..a9ca54a46 100644
--- a/tools/utils.sh
+++ b/tools/utils.sh
@@ -2,12 +2,12 @@
 # Misc utilities for ScoDoc install shell scripts
 
 to_lower() {
-  echo "$1" | tr "[:upper:]" "[:lower:]" 
-} 
+  echo "$1" | tr "[:upper:]" "[:lower:]"
+}
 
 to_upper() {
-  echo "$1" | tr "[:lower:]" "[:upper:]" 
-} 
+  echo "$1" | tr "[:lower:]" "[:upper:]"
+}
 
 norm_ans() {
   x=$(to_upper "$1" | tr O Y)
@@ -15,7 +15,7 @@ norm_ans() {
 }
 
 check_uid_root() {
-  if [ "$UID" != "0" ] 
+  if [ "$UID" != "0" ]
   then
     echo "Erreur: le script $1 doit etre lance par root"
     exit 1
@@ -24,7 +24,7 @@ check_uid_root() {
 
 terminate() {
   status=${2:-1} # default: exit 1
-  echo 
+  echo
   echo "Erreur: $1"
   echo
   exit $status
@@ -95,8 +95,8 @@ set_scodoc_var_dir() {
 }
 
 
-# XXX inutilise 
-gen_passwd() { 
+# XXX inutilise
+gen_passwd() {
   PASSWORD_LENGTH="8"
   ALLOWABLE_ASCII="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz@#$%^&*()_+=-?><"
   SEED=$(head -c4 /dev/urandom | od -t u4 | awk '{ print $2 }')
@@ -110,3 +110,15 @@ gen_passwd() {
   done
   echo "$password"
 }
+
+
+# Status file: indique si l'install s'est complètement déroulée
+create_install_status() {
+  touch "${SCODOC_INSTALL_STATUS_FILE}" || die "can't create ${SCODOC_INSTALL_STATUS_FILE}"
+}
+remove_install_status() {
+  if [ -e "${SCODOC_INSTALL_STATUS_FILE}" ]
+  then
+      rm -f "${SCODOC_INSTALL_STATUS_FILE}"
+  fi
+}