Reduce GRUB Timeout

Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!

Open the file /etc/default/grub with sudo permission.
```
sudo vim /etc/default/grub
```
Update the value assigned to GRUB_TIMEOUT to a smaller one (e.g., 3). Notice that the time unit is second.
```
GRUB_TIMEOUT=3
```
Update the value assigned to GRUB_RECORDFAIL_TIMEOUT to $GRUB_TIMEOUT.
```
GRUB_RECORDFAIL_TIMEOUT=$GRUB_TIMEOUT
```
Update the GRUB.
```
sudo update-grub
```

References