Ubuntu 16.04 screenshot shortcut keys

First, view the shortcut keys

Open "System Settings", click "Hardware" under "Keyboard", then click on the "Shortcut" tab, check "", you can see the various functions of the shortcut keys:
System Settings-keyboard-shortcut keys

Second, if there is no "" option in the shortcut key list, you can customize the shortcut key

1. Enter the following command at the terminal to see how the tool commands are used:

Gnome-screenshot-h

The results of the command run are as follows:

2. Open System Settings-keyboard-shortcut, click "Customize Shortcut", click "+" sign to add custom shortcut key, then click Apply.

Then click "Disable" on the right end of the newly added custom shortcut and type the key for the shortcut you want (e.g. Ctrl + ALT + a)

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Source: https://www.douban.com/note/600423832/

Ubuntu 16.04 shortcut keys