Compressing Files

• Compression makes files smaller; decompression restores them.
• Compressed files must be decompressed to use.

• Re-compressing compressed files doesn’t reduce size further.

• Two compression types:

  • Lossless: no data loss (text, logs).
  • Lossy: Small data loss (used in images/audio to reduce size).

Common Linux Compression Tools

• gzip / gunzip → uses Lempel-Ziv algorithm (.gz)
• bzip2 / bunzip2 → uses Burrows-Wheeler algorithm (.bz2), smaller files but slower
• xz / unxz → uses LZMA (.xz), best compression with good speed

Example

gzip longfile.txt        # Compress → creates longfile.txt.gz
gunzip longfile.txt.gz   # Decompress → restores original file
gzip -l longfile.txt.gz  # gzip Size Check

# Compression formats:
# gzip  → .gz
# bzip2 → .bz2
# xz    → .xz