Xz Command Guide for Linux | Generated by AI

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Question: How do I use the xz command in Linux?

Answer:

Overview

xz is one of the popular compression tools for Linux. It only compresses a single file. xz is considered to be faster than bzip2 and gzip compression tools. The native file format is .xz.

Basic Syntax

xz [options] [file(s)]

Common Operations

1. Compress a File

xz filename.txt

This compresses the file and replaces it with the .xz version (e.g., filename.txt.xz).

You can also use the explicit compress flag:

xz -z filename.txt

2. Decompress a File

xz -d filename.txt.xz

This produces the original file (e.g., filename.txt) in the current working directory.

You can also use the unxz command, which is equivalent:

unxz filename.txt.xz

3. Keep the Original File

By default, xz deletes the original after compression. To retain the original file, use the -k (keep) option.

xz -k filename.txt

4. Set Compression Level

xz has different levels of compression, numbered 0 through 9. The higher the number, the more compression and space savings you will receive, but at the cost of increased memory and CPU usage.

xz -1 filename.txt   # fastest, least compression
xz -6 filename.txt   # default level
xz -9 filename.txt   # best compression, slowest

Level 0 (--fast) provides the fastest compression with a lower ratio. Level 9 (--best) produces maximum compression but requires more time and system resources.

5. View Compression Info

xz -l filename.txt.xz

You can retrieve information about any compressed file using the -l option, which shows the original size, compressed size, and compression ratio.

6. Test Integrity of a Compressed File

xz -t filename.txt.xz

The -t or --test option tests the integrity of a compressed file. It displays an error if the file is not a valid .xz file. If the file is valid, it prints no output (unless -v is also used).

7. Verbose Output / Progress

xz -v filename.txt

The verbose mode monitors the progress of compression or decompression operations and can be enabled using the -v option.

8. View File Contents Without Decompressing

xzcat filename.txt.xz

The xzcat command displays the content of a compressed file but does not actually decompress the file on disk.

9. Compress Multiple Files into a .tar.xz Archive

Since xz compresses only a single file, to compress multiple files into a single .xz archive, you must use the tar command with the -J option.

tar -cJf archive.tar.xz file1.txt file2.txt

To decompress:

tar -xJf archive.tar.xz

10. Multithreaded Compression

Unlike gzip, xz supports multithreading directly, which speeds up compression.

xz -T4 filename.txt    # use 4 threads
xz -T0 filename.txt    # use all available CPU cores

Quick Reference Table

Option Description
-z Compress (default)
-d Decompress
-k Keep original file
-t Test integrity
-v Verbose/progress
-l List archive info
-0 to -9 Compression level
-T[n] Use n threads
-c Write to stdout

Limitations

One major limitation of xz is that it can only compress files, not folders. It also cannot create password-protected compressed files. Use tar for directories and rar or zip for password protection.

References:

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