gzip

Updated

September 4, 2026

Overview

gzip compresses or decompresses files using the DEFLATE algorithm (.gz). It is the most universal compression tool on Unix-like systems — logs, tarballs (tar.gz / .tgz), and HTTP content-encoding all speak gzip. Default behavior replaces the input file with file.gz (use -k / --keep to retain the original on modern gzip).

For better speed/ratio tradeoffs on new pipelines, consider zstd. For maximum ratio on cold archives, consider xz. Keep gzip for compatibility.

Syntax

gzip [options] [file...]
gunzip [options] [file...]
gzcat / zcat [file...]          # decompress to stdout

Common Options

Option Description
-c, --stdout Write to stdout; keep inputs
-d, --decompress Decompress (same as gunzip)
-k, --keep Keep input files
-f, --force Force overwrite / compress links
-n / -N Don’t save / do save original name & time
-q Quiet
-r Recursive directories
-t Test integrity
-v Verbose
-1 … -9 Fastest … best compression (default 6)
-l List compressed size / ratio for .gz files

Examples with Explanations

Compress / decompress

gzip file.txt                 # creates file.txt.gz, removes file.txt
gzip -k file.txt              # keep original
gunzip file.txt.gz
gzip -d file.txt.gz           # same

stdout pipelines

gzip -c file.txt > file.txt.gz
gunzip -c file.txt.gz > file.txt
tar cf - dir | gzip -9 > dir.tar.gz
gzip -dc dir.tar.gz | tar xf -

Level tradeoffs

gzip -1 fast.log              # CPU cheap
gzip -9 archive.dat           # smaller, slower

Test and list

gzip -t file.txt.gz
gzip -l *.gz

Recursive logs

gzip -r /var/log/old/         # careful: compresses in place
find /var/log -name '*.log' -mtime +7 -exec gzip -9 {} +

View without extracting

zcat file.txt.gz | less
zgrep 'ERROR' app.log.gz
zless app.log.gz

Integrity in scripts

if gzip -t backup.gz 2>/dev/null; then
  echo ok
fi

Notes / Pitfalls

  • Without -k, the source file is removed after successful compression.
  • Compressing already-compressed data (jpeg, mp4, .gz) wastes CPU and may grow size.
  • gzip -r is easy to over-apply on system directories — scope with find.
  • Concatenated .gz members are valid; some tools only read the first.
  • Sparse files and special files: stick to regular files.

2026-relevant notes

  • Still the interchange default for tarballs and many APIs.
  • Prefer zstd for local high-volume logs when all consumers support it.
  • pigz provides parallel gzip when you need multi-core compression of large streams.

Additional Resources

  • man gzip