Issue: Leopard and Snow Leopard tag files downloaded from the web, and ask for confirmation before running a downloaded application or script. While this does provide a default layer of security against running downloaded programs, it is also annoying for people who already exercise an appropriate level of caution about trusting downloaded software. (Note that this “feature” does not do anything with regard to checking downloaded files for viruses, preventing malicious software from running, etc. All it does is remind you that it was downloaded – and require an extra button-click – before the application or script can start). How can I disable this behavior?

Solution: Since (approximately) Leopard 10.5.5, I have no longer noticed the really annoying aspect of this feature; namely, that it asked for confirmation every time any given application or file that was downloaded from the web was subsequently opened. Now, it seems to ask only the first time the application or file is opened, which is much more sensible and less annoying. Consequently, I have stopped trying to circumvent this behavior.

For the more easily annoyed, to turn off the quarantine behavior, simply issue the following command in a Terminal window, and then reboot.


Repeat with YES instead of NO to turn the quarantine back on. The quarantine flag can be removed from files that are already downloaded using the following commands:


for Leopard (OS X 10.5), or


for Snow Leopard (OS X 10.6).

OS Version Compatibility: Lion? (unconfirmed), Snow Leopard, Leopard

Update Status: 15 January 2010