A Technical I.T./DevOps Blog
Problem scenario
You know about encapsulation. You know about private methods that are only accessible from inside a class — not outside. You want to encapsulate a method in a class in Python. How do you write such a program?
Solution
“Programmers are most effective if shielded from, not exposed to, the innards of modules not their own.” (This was taken from page 272 of The Mythical Man-Month.)
Here is an example;
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Problem scenario
Atlassian JIRA is not working. The web UI does not have a login page. On the back-end in the logs, you see an error about not finding a suitable driver. (You may get an error about a port number instead. This problem may require a similar solution to the one proposed below for an error about a suitable driver.) You know you have the ojdbc.jar file (or variation thereof) in the correct place.
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Continue reading “How Do You Troubleshoot JIRA Not Working due to Not Finding a Suitable Driver?”
Problem scenario
You have Awk 4.1.3 installed. The default field separator in awk is a space. You want to assign it to a different character — specifically a colon “:”. You have a string with a colon assigned to the variable “y”. You have tried these things:
echo $y | awk -F “:” ‘/1/ {print $NF}’ # this prints nothing
echo $y | awk ‘{FS=”:”; print $1}’ # this prints y
echo $y | awk ‘BEGIN { FS=”:” } /1/ { print $2}’ # this prints nothing
The above commands do not recognize the “:” as the field separator.
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Problem scenario
You want to write a basic Java program to test it out. How do you write a program to accept user input, specifically a number, and print it back to the screen (using the integer data type)?
Solution
1. Install the Java Development Kit if you have not installed it yet. If you are not sure you have it, run javac -version.
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Problem Scenario
You purchased a camera that connects to your computer (e.g., a laptop) with a USB cable. An example may be an SQ9* camera. You now want to use it. The device connects to your laptop via a USB mini to USB A connector. How do you view images on your desktop that are captured with the camera lense?
Solution
(This problem assumes that the camera is not plug-and-play.
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Continue reading “How Do You Use an USB-Connected Local Camera with Your Desktop Computer?”
Problem scenario
SonarQube is listening on the loopback IP address on port 9000. SonarQube is not listening on the external IP address. You want to access the web UI for SonarQube. What should you do?
Solution
Install a web server and configure it to connect to port 9000. Here are the details for using Apache web server on a Red Hat derivative (e.g., CentOS/RHEL/Fedora).
1.
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Problem Scenario
You want to use a key kair to log into AWS instances. You created an AWS EC-2 instance (aka a virtual machine or server) running Linux. You want to connect to this Linux server (a VM). You created a key pair when you created this VM. You downloaded the .pem file. You need a .ppk file to log in. What should you do?
Solution
1.
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Continue reading “How Do You Create a .ppk File from a .pem File?”
Problem scenario
You configured the source repository (in GitHub, GitLab, in BitBucket or elsewhere) to allow your user to have permissions to read the repository. You run git clone but you get a “permission denied” error. What should you do?
Possible solutions
The Linux server you are on may not give your Linux user permissions to write to the destination directory. Can you clone the repository to the /tmp/ directory?
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Problem scenario
You run a playbook, and there are no errors. But the playbook’s simple logic is not working. The file or directory is not being eliminated. Or the unmount of the directory is not working via the mount module. What should you do about a silently failing playbook?
Solution
1. Verify there are no [trailing] spaces in the directory path. If you accidentally quote a space after the last subdirectory or file,
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Problem scenario
A GitLab webhook (aka integration) fails. It used to work as an integration mechanism with Jenkins. The GitLab error message says:
“500 <!DOCTYPE html> … at org.jenkinsci.main.modules.instance_identity.InstanceIdentity.get(InstanceIdentity.java:133)”
Solution
Go to the Jenkins server and reinstall the GitLab plugins.
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