How to change resolution of unknown display in Linux

How to change resolution of unknown display in Linux

Mostly people avoid using Linux as it is more inclined towards commands and not GUI. But some of the distributions like Ubuntu, Mint etc provide good GUI interface to interact and customize things. Using commands will give you a thorough knowledge of the actual things happening inside the system. Like today I connected my laptop to a much bigger display using VGA cable. But my linux distribution based on Debian was not able to recognize this other monitor. Changing the resolution using the normal settings resulted in only two resolution options which were too low. So today we will see how to change resolution of unknown display in Linux.

Here is the normal way to change the display resolution using the settings panel. Jump into Menu -> Settings. After that choose Display out of all the other things. If you have connected your laptop/PC to another monitor/projector/display then you will see both. Select the display whose resolution you want to change. If the display is recognized by the system then you will see various resolution options. But that is not the case for unknown display.

How to change resolution of unknown display in Linux?

We will do this using a preinstalled utility called ‘xRandR’, which can configure the orientation, size and reflection for different output screens. It is really no rocket science, just follow the commands mentioned below and the issue will be resolved.

We will start by checking some information like default available resolutions, frequency and devices connected. Open up your terminal and type in:

# xrandr

Note: You can use sudo if it asks for permission

You will get an output like the one mentioned below. Just remember the connected devices parameter from this.

How to change resolution of unknown display in Linux

xrandr – Available resolution, connected devices

Now you have the available resolutions, connected devices, refresh rates and stuff like that. You can always go ahead and add custom resolutions to xrandr if they are not present in the default file. Next we need to generate the modeline for the desired resolution of our unknown display. Mine is a Samsung Syncmaster monitor with a max resolution of 1440×900.

# cvt 1440 900

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Just substitute your desired values and you will get the modeline like this:


After that we need to define this new mode in the system using ‘newmode’ attribute. Just copy the content from the previous output after Modeline and use it with this command : xrandr –newmode modeline

# xrandr –newmode “1440x900_60.00”  106.50  1440 1528 1672 1904  900 903 909 934 -hsync +vsync


After defining the mode, you need to add it in the system using addmode command.

xrandr –addmode VGA1 1440x900_60.00


VGA1 is the output device parameter taken from the result of first step. 1440×900 is my desired resolution while 60 is the refresh rate. In your case you can refer the modeline for the values. The new resolution is now successfully added and we just need to set it using this command:

# xrandr –output VGA1 –mode 1440x900_60.00

This is the final command which will change the resolution of your unknown display. These commands will just make temporary changes until the system is rebooted. After that the changes will be gone, so we need to add this to the startup default parameters.

You can either make a bash or python script and initialize it to run at the start. Or add these commands to /etc/gdm/init this file. In my case it was gdm3 instead of just gdm. To edit the file simply type:

# nano /etc/gdm3/init


After adding the commands, just give your system a restart and check if everything is working properly. So this is how to change the resolution of unknown display in linux. If you have any doubts please post them in the comment section below.


Make USB bootable Linux or Windows

Guide: How to make USB bootable

I have received a lot of doubts related to installing any operating system. Though if you go ahead and Google the query you will surely find the answers. But then I thought to make my own version of Guide on how to make USB bootable explaining each and everything. I will also recommend some of the software that I use to make USB bootable. So let us begin with the very basic question that is, what is USB bootable?

Guide: How to make USB bootable

What is USB bootable?

Before the trend of USB drives/Pen drives, we all used to install an operating system using a CD/DVD. But now everybody has USB drives which we can use to install the operating system. Now as you know that once you boot your system, after the company branding the operating system kicks in. So if we need to replace that operating system we need to do it before the operating system starts. So all the files of installation comes in a common format called “.ISO”. ISO is basically an image of the optical disc, meaning it has the files copied from the optical disk sector by sector. So if you wanted to generate an exact virtual image of an optical disc, you would do that in the ISO format. All the files are packaged in one single file that ends with a .iso extension. Answering the main question, USB bootable means we will basically copy all the files from the ISO file to USB drive in such a way that it boots on the startup. So one thing is clear that all operating system will come in ISO format.

Where can you find the ISO file?

Well for most of the free Linux distribution it will be available on their respective websites. For Windows you can may be search for it on Google for the official ISO file. For Windows 7/8 I have mentioned a tool below that can also download the ISO file for you. And apart from that you always have one other source where you find all the things which I can’t say it directly but it starts with ‘T’.


  • ISO file of operating system
  • A USB drive of 8GB at least (USB 3.0 would be preferable)
  • A software to make USB bootable

We will be using a software to make USB bootable. It all depends on which operating system you are thinking to install. Nowadays most of the tools support all operating system and are universal. The list of top tools with their download links is given below. Use any one of them.

Software USB bootable:

If you are familiar with Linux then you can also use DD commands which works great too. Before starting with the procedure let me tell you that if you are thinking to dual boot then you can go for the alternative of running the operating system using virtual machine software. Also if you want to do it for DVD then just burn the .iso image directly on it or use the same tools.

GUIDE: How to make USB bootable?

I am going to use Rufus for showing you the procedure.

  1. To begin with make sure that your USB drive is blank and has no files, as this procedure will delete everything.
  2. Next launch any software from the aforementioned link, very few will actually require installtion.
  3. After that it will ask you to choose various things out of which two options are really important. One is USB drive letter and second is .ISO file location. Apart from that the name of operating system may or may not be asked.
    Note: While selecting just choose the option that says I have the ISO file or else it will re-download the whole thing.

    Guide: How to make USB bootable

    Rufus USB bootable Options

  4. After selecting those options you can choose if you want to format the drive or not. Well format is recommended from my side.
  5. So the preparations are done and now you can go ahead click start which will give you some warnings just click yes.
  6. After certain time interval the progress bar will hit 100% and the process will be completed. Now it is safe to remove the USB drive.

This is how to make USB bootable using software and ISO file. There is again one step left before you start the installation which is, go to BIOS setting of your machine and check the boot priority. Always set the boot priority of USB drive to the top so that it boots before the hard disk or DVD-ROM. If you have done the procedure carefully you will see installtion starting. If there is any issue then may be your ISO file is corrupted. If you have any doubts please do mention them in the comment section below.