defaults write com.apple.screencapture location folder_name_here
Save screenshots to the 'Screenshots' folder (inside iCloud Drive)
defaults write com.apple.screencapture location ~/Library/Mobile\ Documents/com~apple~CloudDocs/Screenshots
I am on El Cap also 10.11.6 (15G1004) and while I was able to issue the command, my new screenshot did not save.
Works totally fine on OSX Serria without any issue.
Worked fine for me. I did make the folder before trying it tho. So a
mkdir -p ~/Library/Mobile\ Documents/com~apple~CloudDocs/Screenshots
might be needed on first run.
For the permissions maybe
chmod u+rw ~/Library/Mobile\ Documents/com~apple~CloudDocs/Screenshots
helps?
Using 10.11.6 (15G31) El Cap and it didn't work for me :( It says "Your screen shot can't be saved. You don't have permission to save files in the location where screen shots are stored." If it worked before, something has changed in the OS that now prevents it.