Linux Console – How to Stretch Screen to Fit Monitor

Add something like "vga=792" to the kernel line in your grub.conf file, usually located in /etc or /boot/grub:

title My Linux OS Name and Kernel Version Number
    root (hd0,0)
    kernel /boot/vmlinuz-1.2.3.4 ro root=/dev/hda1 quiet vga=792
    initrd /boot/initrd-1.2.3.4.img

You can say vga=ask instead to get a menu on boot, built from a probing process performed by the kernel to see which resolutions are likely to work. I find that there are often other numbers that will work that this method doesn't find.

This is all system-specific. Different video cards will have different supported modes, and kernel build options can open up or close off video mode options. The subsystem that deals with this is called the kernel framebuffer, so if you're compiling custom kernels, be careful not to remove the support your kernel needs to fully support your video card. Most cards can use the VESA FB driver, but another driver specific to your brand of card might open more options.

Also, beware that some parts of this subsystem use hex numbers, and others decimal. You can do the conversion to decimal, as I've done, or you can say something like "vga=0x318" instead.

I don't think that's possible, as the driver(s) used for the virtual consoles are not that flexible. Once the *fb kernel driver is loaded its settings cannot be changed and once the fbcon module is loaded the *fb wouldn't unload (for me).

However, you just want to enable/disable a monitor and not a full equivalent to xrandr on the console, I think. There is the program vbetool which can interact with hardware a little. Depending on your hardware this tool can enable/disable your lcd panel.

The Linux kernel documentation knows a little about this. In Documentation/power/video.txt lists some alternative tools as well.