2.6 Archiving and Compression

In Linux, “archiving” (bundling many files into one) and “compression” (making files smaller) are often two separate steps, though modern tools combine them.

Archiving with tar

tar (Tape ARchive) is the standard tool for bundling files.

• Create an archive (-c):

  tar -cvf archive.tar file1 file2 dir/

  (Flags: create, verbose, file)

• Extract an archive (-x):

  tar -xvf archive.tar

  (Flags: extract)

• List contents (-t):

  tar -tvf archive.tar

Compression Tools

Linux supports multiple compression formats. gzip is the most common, while xz offers better compression at the cost of speed.

Tool	Extension	Compress	Decompress
gzip	.gz	gzip file	gunzip file.gz
bzip2	.bz2	bzip2 file	bunzip2 file.bz2
xz	.xz	xz file	unxz file.xz
zip	.zip	zip -r arch.zip dir	unzip arch.zip

Combining with tar

You usually don’t compress distinct files; you compress a tarball.

• gzip (-z): archive.tar.gz or .tgz

  tar -czvf archive.tar.gz folder/
  tar -xzvf archive.tar.gz

• bzip2 (-j): archive.tar.bz2

  tar -cjvf archive.tar.bz2 folder/

• xz (-J): archive.tar.xz

  tar -cJvf archive.tar.xz folder/

Backups with rsync

rsync is a powerful tool for synchronization and backups. It only copies changes.

# Sync contents of source to destination
# -a: archive mode (preserves permissions, times, etc.)
# -v: verbose
rsync -av source/ destination/

# Remote sync (over SSH)
rsync -avz source/ user@remote:/backup/DIR/