When you download a file in Mac OS X by default it will quarantine the newly downloaded files and show a prompt asking if you are sure you wish to open the file before allowing it to be accessed. This tweak allows you to disable or enable the quarantine prompt.
Start a new Terminal session (in Finder click Applications > Utilities > Terminal).
To disable this setting, type (or copy and paste) the following command:
defaults write com.apple.LaunchServices LSQuarantine -boolean false
To reset this setting to the default value, type (or copy and paste) the following command:
defaults write com.apple.LaunchServices LSQuarantine -boolean true
To activate this tweak please reboot the system.
Close the Terminal session by typing
exit at the prompt.
Disclaimer: Making any changes to your system can cause serious problems that may require you to reinstall your operating system. We cannot guarantee that problems resulting from these modifications can be resolved. Please follow the instructions carefully and use the information provided at your own risk.