use command -v instead of which. The latter is an alias on some envs

update.sh

@@ -35,7 +35,7 @@ source config.cfg
 # Check dependencies
 deperrors=''
 for depend in curl; do
-  if ! which "$depend" >/dev/null 2>&1; then
+  if ! command -v "$depend" >/dev/null 2>&1; then
     deperrors="$depend $deperrors"
   fi
 done