Many people know how to capture screen into a file on Mac by using Command⌘ + Shift⇧ + 3 for a full screenshot and 4 for cross hair selection tool. However, I found I want to paste the captured image into an editor directly more than saving the image into a file. The hotkey for taking a screenshot to the clipboard is very inconvenient, which is Control + Command⌘ + Shift⇧ + 3 or 4. The following steps show how to reassign the shortcuts for taking a screenshot to the clipboard instead of a file.
1. Go to System Preference and click Keyboard,
2. Click on the second key to reassign Command⌘ + Shift⇧ + 3 for “Copy picture of screen to the clipboard”. It is fine to see the conflict icon as it will be resolved later
3. Click the first key to reassign the Control + Command⌘ + Shift⇧ + 3 , which is less frequnelty using.
4. Do the same for capturing with cross hair selection tool. My personal preference for taking screenshot to a file is Option⌥ + Command⌘ + Shift⇧ + 3 ,