How to prevent Linux 'gdm3' from making the desktop goes to sleep after being inactive for 20 minutes.

 方法一: 

修改 /etc/systemd/sleep.conf

修改其內容相關部份為:

AllowSuspend=no

AllowHibernation=no

存檔後, 重開機即可。

(或是執行 $sudo systemctl daemon-reexec)

方法二:

修改 /etc/gdm3/greeter.dconf-defaults

以及 /usr/share/gdm/greeter.dconf-defaults

以上兩個檔案的內容必須保持一致, 修改之內容相關部份為:

# sleep-inactive-ac-timeout=1200 #--default

sleep-inactive-ac-timeout=0

sleep-inactive-ac-type='blank'

# - As above but when on battery

sleep-inactive-battery-timeout=0

sleep-inactive-battery-type='blank'

修改後, 須重啟電腦方能生效。

(以上二個方法的出處：https://unix.stackexchange.com/questions/529471/debian-10-adjust-sleep-settings-via-command-line)

方法三:

放棄 gdm3，改用 lightdm .

$sudo dpkg-reconfigure gdm3

選單畫面出現後, 改選用 lightdm.