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Working with Files in CentOS
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.

Lab Info
Table of Contents
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Challenge
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 usehead -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. -
Challenge
Gather the Logs
-
Get the format for today's date:
tail /var/log/messages
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Copy and paste the date.
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Run the following, and output it to the terminal to make sure it looks right:
grep "<DATE> " /var/log/messages
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Once we verify it looks right, run:
grep "<DATE> " /var/log/messages > /tmp/logs
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-
Challenge
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, thewc
command will do that for us.Run:
wc -l /etc/passwd > /tmp/usernum
About the author
Real skill practice before real-world application
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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Engage hands-on with the tools and technologies you’re learning. You pick the skill, we provide the credentials and environment.
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All labs have detailed instructions and objectives, guiding you through the learning process and ensuring you understand every step.
Turn time into mastery
On average, you retain 75% more of your learning if you take time to practice. Hands-on labs set you up for success to make those skills stick.