Linux · Systems fluency
How do you create, inspect, and extract archives safely?
Short answer
tar bundles files into an archive, and a compressor such as gzip, zstd, or xz reduces size. List an archive before extracting, and never extract an untrusted archive as root without checking its paths.
An archive preserves paths and metadata; compression is a separate step layered on top. tar can call the compressor for you through flags such as -z for gzip, -J for xz, and --zstd for zstd.
tar -czf app.tar.gz ./dist
tar -tzf app.tar.gz | head
tar -xzf app.tar.gz -C /srv/appCompression choices
- gzip is ubiquitous and fast enough for most cases
- zstd offers a better speed-to-ratio trade-off on modern systems
- xz compresses well but costs more CPU and memory
- zip is useful for cross-platform exchange but stores metadata differently
- Compression level tuning matters more for large, repeated archives
Extract into an empty directory and inspect the file list first. Archives can contain absolute paths, parent-directory references, or symlinks that escape the target directory. Modern tar blocks many of these, but the safest workflow is still to verify before extracting.
Follow-ups you should expect
Interviewers use these to check whether the first answer was understanding or memorisation.
- 1What is the difference between an archive and a compression format?
- 2Why should you list a tar archive before extracting it?
- 3When would you choose zstd over gzip?
- 4What makes a backup different from an archive?
Say it in the interview
tar creates an archive and a compressor reduces its size. I list the archive before extracting and extract into an empty directory, especially for files from outside the team. For backups I verify restores and keep copies off-host, because creating an archive is not the same as having a usable backup.
Use this as a model, not a script. Saying it in your own words is what makes it survive follow-up pressure.
Related questions
Reading is step one
Now say it out loud.
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