Which command would you use to decompress a xz file?

The command used to decompress a .xz file is unxz. This command is specifically designed to handle files compressed with the LZMA (Lempel-Ziv-Markov chain algorithm), which is the algorithm used by the xz compression method. When you execute unxz followed by the file name, it effectively decompresses the xz file back to its original format.

The other options, while related to file decompression, are not suitable for .xz files. For instance, xz -d is indeed a valid command for decompression, as it indicates that you're using the xz command with the option to decompress. However, unxz is the more common and straightforward usage specifically for this purpose.

gzip -d is meant for decompressing files compressed with the gzip algorithm, which is entirely different from xz. Similarly, tar -xvf is a command used for extracting files from tar archives, which may or may not be compressed. It does not directly apply to .xz files unless they are first extracted from a tarball that is compressed with xz, which requires an additional step.

Therefore, unxz is the most appropriate command for decompressing .xz files directly, making it the correct choice.