ubuntu中修改grub的啓動時間

網上查詢修改grub的啓動時間基本上是修改 /etc/default/grub

#註釋掉GRUB_HIDDEN_TIMEOUT=0
#GRUB_HIDDEN_TIMEOUT=0
#修改GRUB_TIMEOUT = 0 
GRUB_TIMEOUT = 0

然後運行update-grub重新生成/boot/grub/grub.cfg.然而這並不管用,依舊要等待30秒

查看/boot/grub/grub.cfg

### BEGIN /etc/grub.d/00_header ###
...
function recordfail {
  set recordfail=1
  # GRUB lacks write support for lvm, so recordfail support is disabled.
}
...
if [ "${recordfail}" = 1 ] ; then
  set timeout=30
...
if [ $grub_platform = efi ]; then
  set timeout=30
...
### END /etc/grub.d/00_header ###

從上面的配置可以看到,如果是lvm分區,則超時時間爲30秒;如果是EFI方式啓動的超時時間爲30秒.優先級EFI > LVM.

再看下生成這段配置的/etc/grub.d/00_header腳本

...
    cat << EOF
if [ "\${recordfail}" = 1 ] ; then
  set timeout=${GRUB_RECORDFAIL_TIMEOUT:-30}
else
EOF
...
if [ "$recordfail_broken" = 1 ]; then
  cat << EOF
if [ \$grub_platform = efi ]; then
  set timeout=${GRUB_RECORDFAIL_TIMEOUT:-30}
  if [ x\$feature_timeout_style = xy ] ; then
    set timeout_style=menu
  fi
...

可以看到這時超時30秒是通過GRUB_RECORDFAIL_TIMEOUT這個值設置的.
所以只需要在 /boot/grub/grub.cfg 加上或修改 GRUB_RECORDFAIL_TIMEOUT

GRUB_RECORDFAIL_TIMEOUT=0

然後運行sudo update-grub重新生成/boot/grub/grub.cfg即可.