IT-230

Linux Administration

Exercise

Creating and Extracting Archives Exercise

Overview

An archive is one file that holds many files, along with the directory structure, ownership, permissions, and timestamps that a plain copy can lose.

In this hands-on exercise you will bundle the entire /etc directory into a single uncompressed archive, read its contents without unpacking it, extract the whole archive into a directory of its own, and then extract just one file from it.

Host
servera
Run as
root

  1. Bundle all of /etc as root into one uncompressed archive under /tmp

    Reading every file under /etc requires administrative privileges, so connect to servera and become root first. 

    ssh student@servera
sudo -i

    -c creates, -v lists each member as it is added, and -f names the archive file. 

    tar -cvf /tmp/etc-backup.tar /etc

  2. Check the size of the archive you produced

    -h prints the size in human-readable units. 

    ls -lh /tmp/etc-backup.tar

  3. Read the archive's contents without unpacking it

    -t lists the members. Notice that every path is stored without its leading slash. 

    tar -tf /tmp/etc-backup.tar | head -n 20

  4. Unpack the archive into an empty directory of its own

    tar unpacks into the current working directory, so change into a directory of its own first. 

    mkdir -p /tmp/etc-extract
cd /tmp/etc-extract
tar -xf /tmp/etc-backup.tar
ls

  5. Confirm the extracted tree looks like the original

    Compare one extracted file against the original. diff printing nothing means the two files are identical. 

    ls -l /tmp/etc-extract/etc | head -n 10
diff /tmp/etc-extract/etc/hosts /etc/hosts

  6. Extract a single file into a fresh directory

    Name the member you want exactly as -t printed it: etc/hosts, not /etc/hosts. 

    mkdir -p /tmp/etc-one
cd /tmp/etc-one
tar -xf /tmp/etc-backup.tar etc/hosts
ls -R /tmp/etc-one