tar — Archive and Extract Files

💬 "tar command"

tar is a tool that bundles multiple files into a single file, and adding -z also applies gzip compression. It is the standard for Linux backup and distribution.

Options are often written together like tar -czvf, and when extracting you change it to -x.

• Concept: c is create (bundle), x is extract (unbundle), and t is list (list contents). These three letters are the core.
• Left letter: operation: c (create) / x (extract) / t (list contents)
• Right letters: options: z (gzip), v (verbose output), f (specify file name, usually at the end)
• Path: When extracting, specify the target directory with -C for safety.
• Result: The extension is conventionally .tar.gz or .tgz.

Commonly used options

Three essential command combinations

• tar -czvf backup.tgz /var/www/html — compresses and backs up the entire web root
• tar -tzvf backup.tgz | head — checks the contents and paths before extracting
• tar -xzvf release.tgz -C /opt/app — extracts safely to the specified directory

💬 "Tell me a tip for using it without overlapping with nightly batch jobs"

This is a step-by-step summary of situations commonly encountered on live production servers.

Step 1 · Decide what to include and create the archive

Choose the backup target, then bundle it into a single file.

tar -czvf /backup/www-20261018.tgz /var/www/html

Step 2 · Check the list before extracting

Check the contents first to prevent extracting to the wrong path.

tar -tzvf /backup/www-20261018.tgz | head -20

Step 3 · Extract to the target directory

Don't overwrite the live directory directly; extract to a separate path and verify.

tar -xzvf /backup/www-20261018.tgz -C /tmp/restore

How it's used in practice

1. Distributing release files

Situation — You need to extract release.tgz, which contains build artifacts, to /opt/app on the production server.

tar -xzvf /tmp/release.tgz -C /opt/app

Result — The list of extracted files is printed to stderr and they are placed under /opt/app.

Point — Specify the production directory with -C, and if possible move the previous version to .bak before extracting for safety.

2. Backing up only configuration files

Situation — You want to back up only the nginx/php configuration separately.

tar -czvf /backup/conf-20261018.tgz /etc/nginx /etc/php

Result — The configuration files are bundled into a single tgz for storage. Because absolute paths are included, their locations are preserved when restoring.

Point — Bundling with absolute paths simplifies restoration. For relative-path archives, make sure to check the base path when extracting.

Things to watch out for

• When extracting, there is a risk of tar bombs (path traversal during extraction). For untrusted files, check the list with -t first.
• Files archived with absolute paths will overwrite their original location when extracted without -C, no matter where you extract them.
• Don't extract directly into a live directory; verify in a temporary path.
• Files being written, such as SQLite/DB files, can lose consistency, so use a separate method.

Actual execution screen

This is the result after checking the list first (top) and then checking the actual backup file size (bottom).

!tar command execution result: archive list and backup file size

Live production server

Source (HTML): https://games.aidebatehub.com/programs/linux/filesystem/tar.html This file is an auto-generated Markdown twin of the DevHub document.