`fts.sh` fails to update `etc/default/grub`

[salvomcl]

Hi,
I've noticed that the code below fails to update the parameter GRUB_CMDLINE_LINUX_DEFAULT in my configuration.

GPU-Passthrough-Manager/tools/fts.sh

Lines 8 to 41 in 762720b

	GRUB=/etc/default/grub
	if [ -f "$GRUB" ]; then
	echo "IOMMU -> GRUB"
	if grep -q iommu "/etc/default/grub"
	then
	echo "IOMMU already enabled"
	else
	if grep -q GenuineIntel "/proc/cpuinfo"
	then
	echo "intel cpu detected"
	sed -i 's/GRUB_CMDLINE_LINUX_DEFAULT="/&intel_iommu=on /' /etc/default/grub
	echo "IOMMU enabled"
	else
	echo "amd cpu detected"
	sed -i 's/GRUB_CMDLINE_LINUX_DEFAULT="/&amd_iommu=on /' /etc/default/grub
	echo "IOMMU enabled"
	fi
	i=1
	fi
	if grep -q rd.driver.pre=vfio-pci "/etc/default/grub"
	then
	echo "VFIO preload already enabled"
	else
	sed -i 's/GRUB_CMDLINE_LINUX_DEFAULT="/&rd.driver.pre=vfio-pci /' /etc/default/grub
	echo "VFIO preload enabled"
	i=1
	fi
	if [ $i -gt 0 ]; then
	echo "Updating GRUB"
	grub-mkconfig -o /boot/grub/grub.cfg
	else
	echo "GRUB already configured"
	fi
	fi

The reason is that the sed pattern is looking for double quotes, while in my /etc/default/grub I have the following line which uses single quotes instead:
GRUB_CMDLINE_LINUX_DEFAULT='nowatchdog nvme_load=YES loglevel=3'.

However, even using the GRUB_CMDLINE_LINUX_DEFAULT above, the gpu passthrough is working flawlessly.
Is there any reason why I should update the GRUB_CMDLINE_LINUX_DEFAULT parameter according the script above?

If useful, I'm using EndeavourOS.

Thanks!