The kind of checksum provided and recommended for checking Ubuntu images these days is a SHA256SUM. But for checking for inadvertent corruption, it's enough to look up the checksum and test your file. For security purposes, it's a good idea to check the GPG signautre on the file providing the checksums (and to avoid MD5 checksums, which are weak against deliberate attacks). Many files available for downloading, including ubuntu-19.10-preinstalled-server-arm64+ all the Ubuntu images, have checksums that can be used to more reliably gauge if the file was completely and correctly downloaded. That addresses most cases of incomplete downloads and a few cases of corrupted downloads, but it is far from perfect. You can use ls -l to find the length of your file in bytes and compare that length to the expected length-for that particular file, the length should be 661217868. If decompression fails with an error message about how the file format is not recognized, then especially if running file on it is unable to identify the format as XZ compressed data (though sometimes otherwise), you likely have a corrupted or incomplete download. Dealing with possibly incomplete or corrupted files
LINUX UNZIP .XZ WINDOWS
But in that case you can just use a Windows method (see the official instructions).
LINUX UNZIP .XZ WINDOWS 10
So if you're running Ubuntu in Windows 10 with WSL, those instructions don't apply. It is not typically possible to write a flash drive with dd in a WSL system. In that case, use this command instead: sudo dd if=ubuntu-19.10-preinstalled-server-arm64+ of= device bs=32M img file, then don't use that command above with xzcat. If you have a corrupted file, xzcat will fail, just as unxz would. Run this command, replacing device with the device name you found: xzcat ubuntu-19.10-preinstalled-server-arm64+ | sudo dd of= device bs=32M Make sure this is not the name of a device that contains any data you wish to keep! One way to do this is in Disks (your file browser). But assuming it's Ubuntu, here's a summary:įind the name of the device that you are writing it to.
The best way to do this differs depending on what operating system you're using to do it. Assuming the file was correctly and successfully downloaded (see below), you can use the official instructions to flash this image to a storage device.
The particular file you've downloaded is a preinstalled image for Ubuntu Server 19.10. Flashing the preinstalled Ubuntu Server image in particular xz file (unless the file is very misleadingly named), only decompression is needed. tar.xz file, since tar supports decompressing and extraction through a single command. Note that this is different from what you would usually do for a. xz file, you can pass the -k/ -keep option: unxz -k ubuntu-19.10-preinstalled-server-arm64+ That will extract ubuntu-19.10-preinstalled-server-arm64+raspi3.img and, assuming it succeeds, delete ubuntu-19.10-preinstalled-server-arm64+. You can uncompress it with: unxz ubuntu-19.10-preinstalled-server-arm64+ Ubuntu-19.10-preinstalled-server-arm64+ is the result of compressing a single file, ubuntu-19.10-preinstalled-server-arm64+raspi3.img, with xz.
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