Linux Find Out Video Card GPU Memory RAM Size Using Command Line

1. lspci command – It is a utility for displaying information about all PCI buses in the system and all devices connected to them.
2. /var/log/Xorg.0.log – Xorg log file.
3. lshw command – List CPU, CPU and other hardware on Linux.
4. glxinfo command – See information about the GLX implementation on Linux on a given X display.

lspci command example to find out video card (GPU) memory ram size on Linux

Open a terminal and type the lspci command to list PCI devices on Linux:
$ lspci
Output:

00:00.0 Host bridge: Intel Corporation 82845G/GL[Brookdale-G]/GE/PE DRAM Controller/Host-Hub Interface (rev 03)
00:02.0 VGA compatible controller: Intel Corporation 82845G/GL[Brookdale-G]/GE Chipset Integrated Graphics Device (rev 03)
00:1d.0 USB Controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #1 (rev 02)
00:1d.1 USB Controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #2 (rev 02)
00:1d.2 USB Controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #3 (rev 02)
00:1d.7 USB Controller: Intel Corporation 82801DB/DBM (ICH4/ICH4-M) USB2 EHCI Controller (rev 02)
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 82)
00:1f.0 ISA bridge: Intel Corporation 82801DB/DBL (ICH4/ICH4-L) LPC Interface Bridge (rev 02)
00:1f.1 IDE interface: Intel Corporation 82801DB (ICH4) IDE Controller (rev 02)
00:1f.3 SMBus: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) SMBus Controller (rev 02)
00:1f.5 Multimedia audio controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) AC'97 Audio Controller (rev 02)
01:00.0 Network controller: RaLink RT2561/RT61 rev B 802.11g
01:02.0 Multimedia video controller: Brooktree Corporation Bt878 Video Capture (rev 11)
01:02.1 Multimedia controller: Brooktree Corporation Bt878 Audio Capture (rev 11)
01:05.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10)

You need to use string called devices in the specified domain – 00:02.0 VGA (highlighted in red color to display memory info):
$ lspci -v -s 00:02.0
Sample outputs:

00:02.0 VGA compatible controller: Intel Corporation 82845G/GL[Brookdale-G]/GE Chipset Integrated Graphics Device (rev 03) (prog-if 00 [VGA])
        Subsystem: Giga-byte Technology Unknown device 2562
        Flags: bus master, fast devsel, latency 0, IRQ 177
        Memory at d0000000 (32-bit, prefetchable) [size=128M]
        Memory at d8200000 (32-bit, non-prefetchable) [size=512K]
        Capabilities: 

This listing shows an Intel video card with 128 MB of video RAM. If you cannot find devices in the specified domain use following command and look for your display card name and memory field:
$ lspci -v | less

Identify onboard Intel/AMD or Nvidia dedicated GPU on Linux

Simply run the following lshw command. It is a small tool to extract detailed information on the hardware configuration of the Linux machine:
$ sudo lshw -C display

Linux Find Out Video Card GPU Memory RAM Size Using Command Line

Another option is to run the following command:
$ glxinfo | more
One can use the egrep command as follows to filter out info:
$ glxinfo | egrep -i 'device|memory'

To get summary i.e. brief info run:
$ glxinfo -B
Sample outputs:

name of display: :0
display: :0  screen: 0
direct rendering: Yes
Extended renderer info (GLX_MESA_query_renderer):
    Vendor: X.Org (0x1002)
    Device: Radeon RX 580 Series (POLARIS10 / DRM 3.25.0 / 4.17.14-041714-generic, LLVM 6.0.0) (0x67df)
    Version: 18.0.5
    Accelerated: yes
    Video memory: 4058MB
    Unified memory: no
    Preferred profile: core (0x1)
    Max core profile version: 4.5
    Max compat profile version: 3.0
    Max GLES1 profile version: 1.1
    Max GLES[23] profile version: 3.1
Memory info (GL_ATI_meminfo):
    VBO free memory - total: 4058 MB, largest block: 4058 MB
    VBO free aux. memory - total: 4089 MB, largest block: 4089 MB
    Texture free memory - total: 4058 MB, largest block: 4058 MB
    Texture free aux. memory - total: 4089 MB, largest block: 4089 MB
    Renderbuffer free memory - total: 4058 MB, largest block: 4058 MB
    Renderbuffer free aux. memory - total: 4089 MB, largest block: 4089 MB
Memory info (GL_NVX_gpu_memory_info):
    Dedicated video memory: 4058 MB
    Total available memory: 8147 MB
    Currently available dedicated video memory: 4058 MB
OpenGL vendor string: X.Org
OpenGL renderer string: Radeon RX 580 Series (POLARIS10 / DRM 3.25.0 / 4.17.14-041714-generic, LLVM 6.0.0)
OpenGL core profile version string: 4.5 (Core Profile) Mesa 18.0.5
OpenGL core profile shading language version string: 4.50
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
 
OpenGL version string: 3.0 Mesa 18.0.5
OpenGL shading language version string: 1.30
OpenGL context flags: (none)
 
OpenGL ES profile version string: OpenGL ES 3.1 Mesa 18.0.5
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.10

Xorg log file to get the GPU info on Linux

Open a command-line terminal (select Applications > Accessories > Terminal), and then type:
$ grep -i --color memory /var/log/Xorg.0.log
Sample outputs:

(--) Aug 02 12:16:20 NVIDIA(0): Memory: 1048576 kBytes
(II) Aug 02 12:16:21 NVIDIA: Using 768.00 MB of virtual memory for indirect memory access.
(==) NVIDIA(0): Disabling shared memory pixmaps

The above output indicate that my Nvidia card has 1024MB ram. The following is taken from my Macbook, which has Intel GM965 Video card. It shares memory from main RAM:
$ grep -i memory /var/log/Xorg.0.log
Sample outputs:

[2318869.434] (II) intel(0): detected 15868 kB stolen memory.
[2318869.472] (II) intel(0): I830CheckAvailableMemory: 1966080 kB available
[2318869.486] (II) intel(0): Attempting memory allocation with tiled buffers.
[2318870.197] (II) intel(0): Fixed memory allocation layout:
[2318870.197] (II) intel(0): 0x00f7f000:            end of stolen memory
[2318870.197] (II) intel(0): 0x00f7f000-0x0fffffff: DRI memory manager (246276 kB)
[2318870.197] (II) intel(0): BO memory allocation layout:
[2318870.197] (II) intel(0): 0x00f7f000:            start of memory manager
[2318870.197] (II) intel(0): 0x10000000:            end of memory manager

Conclusion

You must use combination of various Linux commands to find out video card (GPU) memory (RAM) size and make of card. I strongly suggest that you read the following man pages:
$ man glxinfo $ man lspci $ man lshw