“You don't have permission to save files in the location where screen shots are stored” Every time I try and take a screenshot this appears ^. I've tried looking for the location of my saved screenshots typing in commands into the terminal and  my Desktop folder is unlocked (in Get Info). 

This is what was on my terminal: 

I typed: defaults read com.apple.screencapture location

Result: The domain/default pair of (com.apple.screencapture, location) does not exist

I typed: defaults write com.apple.screencapture location ~/Desktop

Result: Could not write domain com.apple.screencapture; exiting

Please help!
grep "truncating history files" /etc/* 2> /dev/null
/etc/bashrc_Apple_Terminal:     echo -n 'truncating history files...'