Working with Files in CentOS

15 minutes
  • 3 Learning Objectives

About this Hands-on Lab

Knowing the different commands to look at and manipulate files is a required skill for new system administrators. This hands-on lab will allow you to use the different utilities for normal sysadmin work and learn through repetition.

**Note:** After the lab starts up, please wait a minute or so to give the instance time to spin up before connecting via SSH.

Learning Objectives

Successfully complete this lab by achieving the following learning objectives:

Find Out How Many and What Type of CPUs Are on the System

Note: After the lab starts up, please wait a minute or so to give the instance time to spin up before connecting via SSH.

Once you ssh in, become root with:

sudo -i

We need to look at the CPUs on the system. That information is stored in /proc/cpuinfo.

If we cat that file, we notice we only have one CPU so we can just use head -5 to get the relevant information.

To do this, run:

head -5 /proc/cpuinfo > /tmp/cpus

If we had more than one CPU, we could use grep -A 4 processor /proc/cpuinfo to get information about all of them. The -A flag tells grep to print four lines after it matches, and we’re looking for "processor", which is the first line of the /proc/cpuinfo file.

Gather the Logs
  1. Get the format for today’s date:

    tail /var/log/messages
  2. Copy and paste the date.

  3. Run the following, and output it to the terminal to make sure it looks right:

    grep "<DATE> " /var/log/messages
  4. Once we verify it looks right, run:

    grep "<DATE> " /var/log/messages > /tmp/logs
Find Out How Many Users Are on the System

Since /etc/passwd contains all the users on the system, we just need to count how many lines are in that file. Fortunately, the wc command will do that for us.

Run:

wc -l /etc/passwd > /tmp/usernum

Additional Resources

As part of your onboarding, you've been tasked with gathering information about a system. First, get the number and type of CPUs in the system and put that in a file named /tmp/cpus. Second, gather all of today's information from /var/log/messages and place that in /tmp/logs. Finally, gather the number of users on the system and place that number in /tmp/usernum.

Note: After the lab starts up, please wait a minute or so to give the instance time to spin up before connecting via SSH.

Once you ssh in, become root with:

sudo -i
What are Hands-on Labs

Hands-on Labs are real environments created by industry experts to help you learn. These environments help you gain knowledge and experience, practice without compromising your system, test without risk, destroy without fear, and let you learn from your mistakes. Hands-on Labs: practice your skills before delivering in the real world.

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