graphics - How can I find what video driver is in use on my system?

I would like to try a different video display driver, but I'm not sure which one I'm currently using.

What's the simple way to see what driver my system is using currently?

Run lshw -c video, and look for the line with "configuration". The loaded driver is prefixed with "driver=". Example output:

  *-display
       description: VGA compatible controller
       product: Core Processor Integrated Graphics Controller
       vendor: Intel Corporation
       physical id: 2

       bus info: pci@0000:00:02.0
       version: 02
       width: 64 bits
       clock: 33MHz
       capabilities: vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:45 memory:fd000000-fd3fffff memory:d0000000-dfffffff ioport:1800(size=8)

If you want more information about the loaded driver, run modinfo. Output of modinfo i915:

filename:       /lib/modules/2.6.35-24-generic/kernel/drivers/gpu/drm/i915/i915.ko
license:        GPL and additional rights
description:    Intel Graphics
author:         Tungsten Graphics, Inc.
license:        GPL and additional rights
... stripped information for saving space ...
depends:        drm,drm_kms_helper,video,intel-agp,i2c-algo-bit
vermagic:       2.6.35-24-generic SMP mod_unload modversions 

Note that modinfo works on filenames and aliases, not on module names. The majority of the modules will have the same name for the module name and filename, but there are exceptions. One of them is nvidia.

Another way of using these commands in order to show you the file name of the driver would be:

modinfo -F filename `lshw -c video | awk '/configuration: driver/{print $2}' | cut -d= -f2`

When loaded, the command lsmod will show the nvidia module as loaded. modinfo nvidia will error out. Why? Because there is no module named "nvidia", it's just an alias. To resolve the alias you can use modprobe --resolve-alias nvidia. Or to get the whole modinfo in one command:

modinfo $(modprobe --resolve-alias nvidia)