macos
Everything I download will not open. OS X says the file is damaged and can't be opened and should be moved to the Trash. Like Adobe Reader, for PDF documents. JPEG files will not open. Office files will not open. Yet the thumbnail preview is perfect and I can flip the pages to see the information is there. I tried to download OpenOffice for the Office documents but it says the same thing, damaged, cannot open, should be moved to the Trash.
MacBook Air with Mountain Lion
Something like RestoreMeNot or Tinker Tool can be used to selectively control which apps restore their windows and should be able to do what you want.
Alternatively, using ⌥ + ⌘ + W in Preview (and most other apps) will close all currently open windows.
This is part of resume. A feature introduced with Lion.
Per default, windows are restored the next time you open the application. If you want to completly close all windows just one time, you can quit an application using ⌘+⌥+Q instead of the standard ⌘+Q to quit an application.
Type the following command in the Terminal. Then restart the specific application.
In general the syntax is:
defaults write com."producer"."program-name" ApplePersistenceIgnoreState YES
Thus, in your case (Preview.app) it is:
defaults write com.apple.Preview ApplePersistenceIgnoreState YES
If you prefer a graphical interface, you can use TinkerTool.
This application gives you access to additional preference settings and allows to activate hidden features in the operating system.
In order to disable this for all applications do this:
go to System Preferences->General->Restore windows when quitting...
Best Answer
The problem that you are running into is that Gatekeeper is trying to protect you from malware and not only doesn't recognize the developer "signature" of the App you downloaded it "sees" the file was modified by someone/something other than the developer.
Gatekeeper options are found in Apple menu > System Preferences… > Security & Privacy > General tab (El Capitan shown below) under the header "Allow applications downloaded from:"
Even with Gatekeeper turned off, if you get the "Damaged App" message, you still won't be able to open the file
Per Apple's Support site:
Making Gatekeeper more friendly....
The solution to this is in the
info.plistfound inside the app. If you set the following key values ininfo.plist, the App will revert to an "Unsigned App" and allow you to install it.Where is the
info.plistfile located? It's located in the root folder of your App and will be prefaced with the App Name:{My-App-info.plist}NOTE: You will need a program like TextWrangler (free) to open .plist files or the Property List Editor available in XCode. (My preference is to go with TextWrangler)
Opening the file....
Once you edit that file and save it, you will be able to open it by Control clicking (or right clicking) the App and selecting open.
Standard Disclaimer
Gatekeeper is there to protect your Mac from the malware that's ever increasing on the Internet. You should only use this solution with Apps that you fully trust. If you are just randomly downloading software and using this solution to bypass Gatekeeper, you will end up with a compromised system. So, use at your own risk.