How Do You Find the Most Recent Exit Code in Linux?

0 Comments

Problem scenario
When a command stops, it returns an exit code. You want to learn more about exit codes starting with the variable that stores the most recently completed Linux command’s exit code.  Every time you use $? in Linux, you get 0. Why is this?

Solution
There are four links that can help you learn more.  Two are from The Linux Documentation Project (one here and another here). 

…

Continue reading “How Do You Find the Most Recent Exit Code in Linux?”

How Do You Troubleshoot an s3cmd Error About “.s3cfg: None”?

0 Comments

Problem scenario
You are trying to run an s3cmd command (e.g., s3cmd ls), but it is not working.  You run an s3cmd command and you get this:

ERROR: /home/jdoe/.s3cfg: None
ERROR: Configuration file not available.
ERROR: Consider using –configure parameter to create one.

What do you do?

Possible Solution #1
1.  sudo find / -name .s3cfg
2. 

…

Continue reading “How Do You Troubleshoot an s3cmd Error About “.s3cfg: None”?”

How Do You Troubleshoot a Network Problem?

0 Comments

Note:  This posting should help you troubleshoot many different network problems (not just those described in the problem scenario below).  Possible solutions 1 through 5 are ideal for erratic nmap results (inconsistent or discrepant output). 

Problem scenario
A port seems blocked on a Linux server given the results of nmap. The host appears to be down. You know this port is not blocked by intermediate routers and/or firewalls. 

…

Continue reading “How Do You Troubleshoot a Network Problem?”

New Year’s Eve in America and around the World

0 Comments

Happy New Years!

In Scotland New Year’s Eve is called “Hogmanay.”  In other countries outside the U.S. it is called “Old Year’s Day” or “Saint Sylvester’s Day.”  In America New Year’s Eve is celebrated with a variety of different traditions.  Many states have their own unique traditions of dropping or lowering of different objects (e.g., a large ball in Times Square in New York City).  

…

Continue reading “New Year’s Eve in America and around the World”

How Do You Change the Duration of Re-Prompting a User to Enter the Password after Running a sudo Command in Ubuntu Linux?

0 Comments

Problem scenario
When users run a command with “sudo ” in front of it, they are prompted for a password.  They are not prompted for a password again for a while.  They can go  15 minutes of using “sudo ” commands with no prompt for a password.  

You want to harden your environment and make them re-enter the password every three minutes in case they leave their desk shortly after they have used sudo.  

…

Continue reading “How Do You Change the Duration of Re-Prompting a User to Enter the Password after Running a sudo Command in Ubuntu Linux?”

How Do You Change a User’s Password When You Cannot Log into Your Azure Linux VM?

0 Comments

Problem scenario
You have a Linux VM in Azure but you cannot log in.  You cannot remember a single password for the username you were using.  What do you do when you forgot all the credentials of a Linux VM except one username?  How can you log into this server?

Solution
Prerequisite
To reset access to the VM in the following way,

…

Continue reading “How Do You Change a User’s Password When You Cannot Log into Your Azure Linux VM?”

How Do You Get the Binaries for kube-proxy, kube-apiserver, kube-controller-manager, and kube-scheduler?

0 Comments

Problem scenario
You want to install kube-proxy, kube-apiserver, kube-controller-manager, and kube-scheduler on a Linux server.  You want to be able to run these commands. How do you do this?

Solution

Prerequisite
This requires the Linux server to have access to the internet.

Procedures
1.  Download the first tar ball.

cd /usr/bin
sudo wget https://github.com/kubernetes/kubernetes/releases/download/v1.8.6/kubernetes.tar.gz
# To get the latest version,

…

Continue reading “How Do You Get the Binaries for kube-proxy, kube-apiserver, kube-controller-manager, and kube-scheduler?”

How Do You Know If Maven Has a Plugin for Apache Parquet?

0 Comments

Problem scenario
You have Maven installed.  You want to know if it has the plugin for Apache Parquet from the Linux terminal.  You do not want to use the Maven GUI.  What do you do?

Solution
1.  sudo find / -name pom.xml  
2.  Change to the directory of the pom.xml with Apache Parquet.
3.  Run this command:
mvn help:effective-pom | grep -i parquet

…

Continue reading “How Do You Know If Maven Has a Plugin for Apache Parquet?”

How Do You Install a Pythonic Implementation of Apache Thrift?

0 Comments

Problem
You want thriftpy installed to deploy Apache Parquet.  How do you install thriftpy?

Solution
Prerequisite
Install pip.  If you need assistance, click on the link according to your distribution of Linux:
CentOS/RHEL/Fedora (most newer versions)
RHEL 6.x
Debian/Ubuntu
SUSE

Procedure
Run this command:  pip install thriftpy

…

Continue reading “How Do You Install a Pythonic Implementation of Apache Thrift?”