Add custom motd

wo/cli/templates/wo-update.mustache

@@ -0,0 +1,37 @@
+#!/bin/sh
+# script to update motd when a new WordOps release is available on Debian/Ubuntu
+# the script is added in /etc/update-motd.d
+
+safe_print() {
+    cat "$1" | head -n 10 | tr -d '\000-\011\013\014\016-\037' | cut -c -80
+}
+
+# Ensure sane defaults
+[ -n "$URL" ] || URL="https://github.com/WordOps/WordOps/releases/latest"
+[ -n "$WAIT" ] || WAIT=5
+[ -n "$CACHE" ] || CACHE="/var/cache/motd-wo"
+
+# Generate our temp files, clean up when done
+NEWS=$(mktemp) || exit 1
+ERR=$(mktemp) || exit 1
+CLOUD=$(mktemp) || exit 1
+trap "rm -f $NEWS $ERR $CLOUD" HUP INT QUIT ILL TRAP BUS TERM
+
+if [ -n "$(command -v curl > /dev/null 2>&1)" ]; then
+    LATEST_RELEASE=$(curl -m 5 --retry 3 -sI "$URL" | grep tag | awk -F "/" '{print $8}' 2>&1)
+fi
+if [ -n "$(command -v wo > /dev/null 2>&1)" ]; then
+    CURRENT_RELEASE=$(wo -v 2>&1 | grep v | awk -F " " '{print $2}')
+fi
+if [ -n "$CURRENT_RELEASE" ] && [ -n "$LATEST_RELEASE" ]; then
+    if [ "$CURRENT_RELEASE" != "$LATEST_RELEASE" ]; then
+        # display message with motd-news on Ubuntu
+        echo '*** A new WordOps release is available ***' > "$NEWS" 2> "$ERR"
+
+        echo
+        # At most, 10 lines of text, remove control characters, print at most 80 characters per line
+        safe_print "$NEWS"
+        # Try to update the cache
+        safe_print "$NEWS" 2> /dev/null > $CACHE || true
+    fi
+fi