After upgrading from OS X Yosemite to OS X El Capitan Developer Preview, I tried to edit /System/Library/LaunchDaemons/ssh.plist to change the default SSH
I use carbon copy cloner to make clonable backups... and have several in rotation.
According to mike at bombich "SIP only applies to the volume you're currently booted from, so [one can] boot from the backup volume to delete [files]".
I did use johannes' answer (recovery drive, csrutil enable/disable), but that requires reboot —> recovery drive —> turn sip off —> reboot —> delete crap —> reboot —> recovery drive —> turn sip back on —> reboot ... four reboots.
But booting from a clone and seeing the original drive as a secondary drive would allow you to delete problematic files in two reboots... yes?
I would suggest you try adding whatever arguments you need to a plist in /Library/Preferences/. For example, in my case I needed to make a slight alteration to mDNSResponder to add the AlwaysAppendSearchDomains flag. As suggested by "bwells" on the Apple developer forums, I just had to do
sudo launchctl unload /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
sudo defaults write /Library/Preferences/com.apple.mDNSResponder.plist AlwaysAppendSearchDomains -bool YES
sudo launchctl load /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
This is a much cleaner approach and persists across reboots and should also survive an upgrade (at least during the betas my manual changes after disabling SIP were overwritten). Note, as far as I know this is new to El Capitan.
You can "by pass" the SIP protection by modifying permissions on file via Finder app for the system group.
modifying permissions
It worked fine for me even after reboot, i'm running
ProductName: Mac OS X
ProductVersion: 10.11
BuildVersion: 15A284
You can also temporarily disable SIP the following way
csrutil disable
csrutil enable
Until 10.11 unprotects certain files in /System/Library or allows you to do it yourself, the only way without disabling SIP would be to make a different service by coping the file somewhere else, like:
sudo cp /System/Library/LaunchDaemons/ssh.plist /Library/LaunchDaemons/ssh.plist
And then instead of using the Sharing panel in System Preferences, you would manage the service yourself:
sudo launchctl unload /Library/LaunchDaemons/ssh.plist
sudo launchctl load -w /Library/LaunchDaemons/ssh.plist
You can also leave SIP enabled while disabling the filesystem management. Reboot in recovery mode and run:
csrutil enable --without fs
This will allow you to change permissions as needed.