ch "sudo" availability check to POSIX

Author: Anton-Latukha

scripts/install-nix-from-closure.sh

@@ -378,7 +378,7 @@ installNix() {
         if sh -c "$cmd" > /dev/null 2>&1 ; then
             print "Creating $dest directory by running $cmd using $USER rights"
         else
-            if which sudo > /dev/null 2>&1 || type sudo > /dev/null 2>&1 ; then
+            if command -v sudo > /dev/null 2>&1 ; then
                 print "Creating $dest directory by running $cmd using sudo:"
                 if sudo -n true 2> /dev/null ; then
                     print "Checked: sudo access does not require password."