Can't edit text files in /Applications folder

Question

Can't edit text files in /Applications folder

I was able to modify the /Applications/Mail.app/Contents/Resources/Message.css file in Yosemite but El Capitan won't let me do it. I am the only user on this computer and I am the Admin. I have tried sudo vi and sudo nano in Terminal but none of them worked. Terminal shows an error message when attempting to modify the file saying "Operation not permitted."

TextWrangler and Sublime Text didn't open the file with write permission as well.

I checked out the permission settings in Finder > Get Info but settings are greyed out. Chmod is currently 644 and the Resources folder is 755.

I also made sure that Mail app was closed (completely Quit) while attempting to modify file.

Please help.

Posted on Sep 30, 2015 5:28 PM

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Answer 1

Niel

Level 10

742,109 points

Sep 30, 2015 5:35 PM in response to Community User

Restart with the Command and R keys held down, and turn off System Integrity Protection for just long enough to make the change.

(134213)

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Answer 2

Sep 30, 2015 5:41 PM in response to Niel

I was not able to see any option about "System Integrity Protection". There were options for Disk Utility, Reinstall, Terminal etc. What am I missing?

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