linuxexpert-practice-labs/labs/linux-plus/1-6-1-archives-and-compression/README.md

Linux+ 1.6.1: Archives and compression

tar archives, restoring one file, gzip, bzip2 and xz side by side, reading a compressed log, and cpio.

Before you start

The lab clears away the files the tasks create in /tmp, if they're there. Ubuntu empties /tmp at boot, so do the tasks without a reboot, and run le-lab check before the chapter's clean-up step (le-lab reset cleans up too, and removes bzip2 again if it wasn't installed when the lab started). Tasks 2 and 3 ask for findings: write them to the files in /root/lab-answers/ that they name.

Tasks

1. Archive /etc into /tmp/etc.tar.gz with gzip, list it to find sshd_config, and restore just etc/ssh/sshd_config from it into /tmp/restore.
2. Install bzip2 if it's missing (it often is). Archive /etc without compression into /tmp/etc.tar. Copy it to /tmp/t-gzip.tar, /tmp/t-bzip2.tar and /tmp/t-xz.tar, and compress each with the tool it's named after, keeping the copies. Write the name of the tool that made the smallest file to /root/lab-answers/2.
3. Save the last 500 lines of the journal, compressed with gzip, as /tmp/j.gz. Without unpacking it, count the lines that mention error in any case, and write the count to /root/lab-answers/3.
4. From /etc, make a cpio archive of the files in ssh as /tmp/ssh.cpio, and unpack it into /tmp/c.

Hints

• tar -czf, tar -tzf, tar -xzf ARCHIVE -C DIR MEMBER.
• dnf install bzip2 or apt install bzip2. gzip -k, bzip2 -k, xz -k; ls -lh /tmp/t-*. The tools skip a file whose name already ends in their own suffix (.gz, .bz2, .xz).
• journalctl -n 500 --no-pager | gzip > ...; zgrep -c -i, zless.
• cd /etc && find ssh -type f | cpio -o > ...; cpio -idv < ....