diff --git a/docker/check.rocketchat.update b/docker/check.rocketchat.update
new file mode 100755
index 0000000..6d08d04
--- /dev/null
+++ b/docker/check.rocketchat.update
@@ -0,0 +1,55 @@
+#!/bin/sh
+# Purpose {{{
+## Create a temp file (to monitor) if an upgrade is available for rocket.chat
+## image on the Docker Hub.
+## How-to use {{{
+### 1. Needs imagetags script, in the same directory
+### cf. https://git.ipr.univ-rennes1.fr/cellinfo/scripts/src/master/docker/imagetags
+# wget https://git.ipr.univ-rennes1.fr/cellinfo/scripts/raw/master/docker/imagetags
+### 2. Ensure to run with a user member of the docker group.
+### 3. Create a cron job, eg.
+#00 20 * * * root /opt/repos/ipr.scripts/docker/check.rocketchat.update
+### 4. Monitor the temp file.
+# Or enable MAILTO in cronjob and print a message in the script.
+# Or send a mail.
+# …
+## }}}
+# }}}
+
+# Vars {{{
+DEBUG=1
+
+script_wd=$(dirname "${0}")
+
+rkt_repo_name="rocketchat"
+rkt_image_name="rocket.chat"
+
+rkt_current_version=$(docker container ls | grep -- "${rkt_repo_name}/${rkt_image_name}" | sed -- "s/.*${rkt_repo_name}\/${rkt_image_name}:\([^ ]*\) .*/\1/")
+
+rkt_grep_pattern="[[:digit:]]\\.\\+[[:digit:]]*\\.\\?[[:digit:]]*$"
+rkt_new_version=$("${script_wd}"/imagetags "${rkt_repo_name}/${rkt_image_name}" "${rkt_grep_pattern}" | tail -n1)
+
+rkt_new_version_file="/tmp/.docker.rocket.chat.upgrade"
+# }}}
+
+# Check if a container already runs with the wanted image {{{
+if [ ! $(docker container ls | grep -q -- "${rkt_repo_name}${rkt_image_name}") ]; then
+	[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Test ${rkt_image_name} — Current version is ${rkt_current_version}."
+else
+	[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Test ${rkt_image_name} — No container runs with ${rkt_image_name} image on this host."
+	exit 1
+fi
+# }}}
+
+# Check if the current version is the last one {{{
+if [ "${rkt_current_version}" != "${rkt_new_version}" ]; then
+	[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Test version — An upgrade is available for ${rkt_image_name}: ${rkt_new_version}."
+	# Create a temp file to monitor
+	touch -- "${rkt_new_version_file}"
+else
+	[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6s\e[m\n' "DEBUG : Test version — The current version is up-to-date."
+	rm -f -- "${rkt_new_version_file}"
+fi
+# }}}
+
+exit 0
diff --git a/docker/imagetags b/docker/imagetags
index e8ac069..839b0d3 100755
--- a/docker/imagetags
+++ b/docker/imagetags
@@ -20,7 +20,7 @@ HELP
 fi
 
 image="$1"
-tags=$(wget -q https://registry.hub.docker.com/v1/repositories/"${image}"/tags -O -  | sed -e 's/[][]//g' -e 's/"//g' -e 's/ //g' | tr '}' '\n'  | awk -F: '{print $3}')
+tags=$(wget -q https://registry.hub.docker.com/v1/repositories/"${image}"/tags -O - | sed -e 's/[][]//g' -e 's/"//g' -e 's/ //g' | tr '}' '\n' | awk -F: '{print $3}')
 
 if [ -n "$2" ]
 then