Problem Statement
Which command creates compressed archives for backup?
Explanation
Tar (tape archive) creates archives, often compressed. Common usage: tar -czf archive.tar.gz /path/to/backup creates compressed archive, tar -xzf archive.tar.gz extracts. Flags: -c (create), -x (extract), -z (gzip compression), -j (bzip2), -J (xz), -f (file), -v (verbose), -t (list contents).
Examples: tar -czf backup-$(date +%Y%m%d).tar.gz /home backs up /home directory, tar -xzf archive.tar.gz -C /restore extracts to specific directory. Exclude: tar --exclude='*.log' -czf archive.tar.gz /data excludes log files.
Other backup tools: rsync (efficient incremental backups), dd (disk cloning), dump/restore (ext filesystem backup), borgbackup (deduplicating backups). Best practices: test backups regularly, store offsite, automate with cron, encrypt sensitive data, document restore procedures.
Backup strategies: full (complete backup), incremental (changes since last backup), differential (changes since last full). 3-2-1 rule: 3 copies, 2 different media, 1 offsite. Understanding backup tools prevents data loss.
