Insert Pen Drive which you want to make bootable.
If you don’t have Windows OS then use Bootable Drive Maker tool on your Mac.
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If in case you want to install Linux along with Mac OS as a dual boot then follow the below method. So this way you can change to Linux from Mac OS. Note: If you find WiFi connectivity issue then connect with ethernet and update the OS if available.
And then load the downloaded Ubuntu iso file. Click on the small disc icon (or SELECT in the newer version) just next to the ISO image drop down menu.
Make sure Pen Drive is attached to your Windows PC. Run Rufus on your PC as an administrator.If you don’t have a Windows PC then use Bootable Drive Maker tool which is available for Mac. You need a tool to create a bootable drive so download Rufus for this.You can download the version with long term support. Download the Ubuntu OS from its official website.So if you prefer dual boot then follow the second method and skip this one. Here we are going to install Ubuntu as a single system on the MacBook. Method 1: Steps to Install Linux on MacBook