Linux: How to change the text size or character size in runlevel 3 (text mode)

If you have large size (21″) or small size (14″) monitor, it is better to use large/small character size. But how do you setup character size in runlevel 3 under Linux?

The answer is simple, use the kernel framebuffer. It allows you to set the Linux text scree (console) to higher or lower resolution. The Linux framebuffer (fbdev) is a graphic hardware-independent abstraction layer to show graphics on a console without relying on system-specific libraries such as SVGALib or the heavy overhead of the X Window System.

Open GRUB configuration file grub.conf
# vi grub.conf

Append line vga=0x318 (a 24-bit color depth @ 1024×768 display) to kernel line. At the end your modification should look like as follows:
title Debian Linux, AMD-VSNL (VMWARE)
root (hd1,0)
kernel /boot/vmlinuz-2.6.17.11-ROCKY-DEV-AMD root=/dev/hdb1 ro vga=0x318
initrd /boot/initrd.img-2.6.17.11-ROCKY-DEV-AMD
savedefault
boot


Save and close the file. Reboot the system:
# reboot

0x318 (hex) is a mode. Here are common modes:

See kernel docs – Documentation/i386/boot.txt and Documentation/svga.txt files for more information. You can also pass special parameter called ask i.e. vga=ask for menu.

Please note that not all video cards out there support kernel framebuffer mode. Also you may need to to use special driver.

References:

• 10 boot time parameters you should know about the Linux kernel
• Framebuffer HOWTO