How do you zip files using Red Hat Enterprise Linux (or CentOS or Fedora Linux)?

Goal:  You want to use zip when you are using Red Hat Enterprise Linux (or CentOS or Fedora Linux).
Background:  The zip character-based utility is useful for many reasons.  At the command line you can free up space while retaining files for future usage.  Try this command to see if zip is installed: man zip

Part 1:  How to install zip?
If the command cannot be found,

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How Do You Assign a Password to a Variable In Linux Without Making It Visible?

Goal:  You want to issue a command (e.g., an export command) that has a password in it.  But you do not want anyone looking over your shoulder to see it.  You do not want the password to be visible in the history of the shell.
Solution:  Type this ‘read -s foobar’
Then press enter.  The cursor will go to the next line.  Type in the password.  The characters will not echo to the screen. 

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How to Troubleshoot PowerShell Downloading a File From the Internet

Problem scenario:  When trying to use PowerShell to download a file, get you this error ‘Error calling “DownloadFile” with “2” argument(s): “An Exception occurred during a WebClient request.”‘

Solution:  Make sure you have ample space on the disk and make sure the destination folder exists.  A typo in the path or if the folder not existing could cause this error.  Insufficient disk space could also cause the problem. 

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How to Install Hadoop on an AWS Instance of RedHat Linux or an Azure Instance of CentOS

Updated 1/5/18

THESE DIRECTIONS ARE OUTDATED.  They are here as a reference for legacy purposes only.  For directions on how to install Hadoop on a RedHat or CentOS server, see this article.

Problem scenario
You want to install an open source version on a RedHat derivative distribution of Linux in a public cloud.  How do you do this?

Solution
These directions will allow you install Hadoop on a RedHat derivative (e.g.,

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How to Install Suricata on an AWS Instance of SUSE Linux

These “directions” to install Suricata on SUSE Linux include a script and how to run it.  The script was designed to install Suricata 3.1dev on an AWS instance of SUSE 12 SP1.  This script was based on these here. This script requires that your AWS SUSE Linux server is in a security group that has access to the Internet.  The script takes approximately five minutes to run.  But bandwidth and resources on your instance may vary.

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How To Get Hadoop Installed on Ubuntu When There Is a Java Error

Problem scenario:  On Ubuntu, after installing Hadoop, when you enter the command ‘/usr/local/hadoop/bin/hadoop namenode -format’ and you get this error:

“Error: JAVA_HOME is not set and could not be found.”

Solution:  Verify Java is installed (‘java -version’).  If it is not installed, you can use ‘apt-get install -y default-jre’.

Next, go to hadoop-env.sh.  Find the export JAVA_HOME stanza.  Change the ‘${JAVA_HOME}’ value to ‘/usr’ with no quotes.

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How Do You Get All the Security Updates and OS Updates for Your Ubuntu Server to Be Applied?

Problem scenario
When you log into Ubuntu, you see a message like this:

8 packages can be updated.
5 updates are security updates.

You run this: sudo apt-get -y update

This completes.  But next time you log in, you see the same message about 8 packages can be updated.  What do you do?

Solution
Run this command:  sudo apt-get -y upgrade

If you are looking for deploying Hadoop to Ubuntu,

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How to Install Suricata on an AWS Instance of Ubuntu Linux

Updated on 11/28/17

Problem scenario
You want to install Suricata on Ubuntu Linux.  How do you do this?

Solution
These directions to install Suricata on include a script and how to run it.   The optional script in 2.c was based on these here.  The optional script in 2.c script requires that your AWS Ubuntu Linux server is in a security group that has access to the Internet. 

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How to Use Ant (when You Receive an Error about build.xml Not Existing)

Problem Scenario:  You want to use Ant to invoke your customized build.xml file.  But when you run it, you get “
Target “build.xml” does not exist in the project …”
Solution:  Call ant with no other variables.  Do not use “ant build.xml”.  Use “ant” by itself.
Miscellaneous:  Most CentOS/RedHat repositories will have Ant available.  As root, the command “yum install ant” should get it installed. 

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What Are the Minimum Packages Necessary for Kerberos on CentOS?

Question 1:  What are the packages that must be installed on a CentOS server to have it serve as the Kerberos server?

Answer 1: These three packages: krb5-server krb5-libs krb5-auth-dialog

Question 2:  What are the packages that must be installed on a CentOS server to have it serve as the Kerberos client?