better detection for whether app is installed

update.sh

@@ -32,15 +32,22 @@ cd "$(dirname "$(readlink -f "$0")")"
 if [ ! -e config.cfg ]; then echo "Missing config.cfg file. Edit and rename config.cfg.sample"; exit 1; fi
 source config.cfg
 
-# Test whether necessary applications are installed
-function testinst {
-  APP=$1
-  if [ $(which $APP | wc -l) != 1 ]; then
-    echo "$APP does not seem to be installed. Aborting."
+# Check dependencies
+deperrors=''
+for depend in curl; do
+  if ! which "$depend" >/dev/null 2>&1; then
+    deperrors="$depend $deperrors"
+  fi
+done
+if [ -n "$deperrors" ]; then
+  cat <<-EOF
+	This program depends on some other programs to function.
+	Not all of those programs could be located on your system.
+	Please use your package manager to install the following programs:
+	EOF
+  echo "$deperrors"
   exit 1
 fi
-}
-testinst curl
 
 USERDB=users.db