use install to copy file

acme-downloader.sh

@@ -184,22 +184,25 @@ check_version
 VERSION_STATUS=$?
 
 if [[ -n $FORCE_UPDATE ]]; then
-    curl $SCRIPT_URL -o ${0}.new
+    TMP_UPDATE=$(mktemp)
+    curl $SCRIPT_URL -o $TMP_UPDATE
     UPDATE_STATUS=$?
     if [ $UPDATE_STATUS == 0 ]; then
-        rm -f $0; mv ${0}.new $0; chmod 0755 $0
+        install --owner=root --group=root --mode=0755 -T $TMP_UPDATE $0
         echo -e "\n$0 updated successfully\n"
     else
         echo -e "\nfailed to update $0"
         echo -e "Please download the script manually from this URL: ${SCRIPT_URL}\n"
     fi
+    rm -f $TMP_UPDATE
     clean_up $UPDATE_STATUS
 fi
 
 if [[ -n $UPDATE ]]; then
+    TMP_UPDATE=$(mktemp)
     UPDATE_STATUS="skip"
     if [ $VERSION_STATUS -eq 1 ]; then
-        curl $SCRIPT_URL -o ${0}.new
+        curl $SCRIPT_URL -o $TMP_UPDATE
         UPDATE_STATUS=$?
     fi
     if [ $UPDATE_STATUS == "skip" ]; then
@@ -207,13 +210,15 @@ if [[ -n $UPDATE ]]; then
         echo -e "\n$0 is already up to date\n"
     elif [ $UPDATE_STATUS -eq 0 ]; then
         EXIT_STATUS=0
-        rm -f $0; mv ${0}.new $0; chmod 0755 $0
+        install --owner=root --group=root --mode=0755 -T $TMP_UPDATE $0
+        rm -f $TMP_UPDATE
         echo -e "\n$0 updated successfully\n"
     else
         EXIT_STATUS=$UPDATE_STATUS
         echo -e "\nfailed to update $0"
         echo -e "Please download the script manually from this URL: ${SCRIPT_URL}\n"
     fi
+    rm -f $TMP_UPDATE
     clean_up $EXIT_STATUS
 fi