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Managing file sizes is essential for saving disk space and speeding up transfers. In this guide, you’ll learn how to compress and decompress files and directories using the most common Linux utilities: gzip, bzip2, xz, zip, and tar.

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Table of Contents

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Compression Tools Overview

Linux distributions typically include these single-file compressors by default:
UtilityFile ExtensionCompression RatioTypical Speed
gzip.gzModerateFast
bzip2.bz2BetterModerate
xz.xzBestSlow
Each tool replaces the original file with the compressed version unless instructed otherwise.

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Compressing and Decompressing Single Files

Use the following commands to compress and decompress individual files: 
# Compress
gzip   file1       # → file1.gz
bzip2  file2       # → file2.bz2
xz     file3       # → file3.xz

# Decompress
gunzip   file1.gz   # → file1
bunzip2  file2.bz2  # → file2
unxz     file3.xz   # → file3
Alternatively, use the long options for clarity: 
gzip  --decompress file1.gz
bzip2 --decompress file2.bz2
xz    --decompress file3.xz
By default, gzip, bzip2, and xz delete the original file after (de)compression. Use -k or --keep to preserve input files.

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Preserving Original Files

To keep both the source and the compressed version, add the -k (keep) flag: 
gzip  --keep file1       # Keeping file1 and creating file1.gz
bzip2 --keep file2       # Keeping file2 and creating file2.bz2
xz    --keep file3       # Keeping file3 and creating file3.xz
You can confirm the flag via: 
gzip --help | grep -E '^-k, --keep'
#  -k, --keep   keep (don't delete) input files

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Inspecting Compressed Archives

To view metadata (compressed size, uncompressed size, compression ratio), use the --list (-l) option: 
gzip --list file1.gz
# compressed  uncompressed  ratio uncompressed_name
bzip2 --list file2.bz2
xz    --list file3.xz

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Working with ZIP Archives

Unlike gzip/bzip2/xz, the zip utility can bundle multiple files or directories into a single archive: 
# Create or update archive.zip with file1
zip archive.zip file1
# Recursively add a directory
zip -r archive.zip Pictures/
# adding: Pictures/ (stored 0%)
# adding: Pictures/family_dog.jpg (stored 0%)
To extract everything from a ZIP archive: 
unzip archive.zip
# Archive: archive.zip
#   inflating: file1
#   inflating: Pictures/family_dog.jpg

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Combining tar with Compression

Since gzip, bzip2, and xz operate on single files, tar is used to first archive multiple files/directories, then compress the archive.

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Two-Step Archiving

# 1. Create an uncompressed tarball
tar --create --file archive.tar file1 file2 dir1/

# 2. Compress the tarball
gzip archive.tar         # → archive.tar.gz
# or
bzip2 archive.tar        # → archive.tar.bz2
# or
xz archive.tar           # → archive.tar.xz

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One-Step Archiving with Compression

Leverage tar’s built-in compression flags: 
tar --create --gzip   --file archive.tar.gz  file1 file2 dir1/
tar --create --bzip2  --file archive.tar.bz2 file1 file2 dir1/
tar --create --xz     --file archive.tar.xz  file1 file2 dir1/
Or use auto-compression (-a) to match the extension: 
tar --create --auto-compress --file archive.tar.gz file1
# shorthand
tar caf archive.tar.xz file1

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Extracting Compressed Tarballs

tar will detect compression automatically: 
tar --extract --file archive.tar.gz
tar xf archive.tar.bz2
tar xf archive.tar.xz

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References

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