A Technical I.T./DevOps Blog
Problem scenario
On a CentOS server running in VirtualBox, networking is not working. You cannot ping the default gateway or get to the internet. When you try to ping something, you get the error message in a terminal “connect network is unreachable.” What should you do?
Solution
In Oracle VirtualBox, go to Devices -> Network Settings. Make sure the adapter is attached to “Bridged Adapter”.
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Problem scenario
In MacOS you want to edit a screenshot or some image or picture file. What do you do (to not use Preview’s view only format)?
Solution
Prerequisite
To take a screenshot, hold Command, Shift and tap the numeral “5” key. Using all three simultaneously will allow you to capture the screen.
Procedures
In Preview near the top,
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Continue reading “Using a Mac, How Do You Modify a Screenshot?”
Problem scenario
You have read about lists or arrays being rotated. What does this mean in computer programming?
Solution
Lists and arrays can be interchangeable in many contexts. Java supports arrays and Python supports lists. Both are zero-based. That is, the first item in each is indexed as 0. Lists in Python are circular: the last item in the list can be referred to as -1 and the penultimate item can be referred to as index -2.
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Continue reading “What Is Rotating a List in Computer Programming?”
Problem scenario
You want to view the emails in a .mbox file. You are using Thunderbird. What do you do?
Solution
Overview: Install the ImportExportTools NG add-on. Have another email account (an empty one or something else) that can accept the emails in Thunderbird configured.
Procedures
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Continue reading “How Do You Import a .mbox into Thunderbird to View the Emails?”
Question
Surfing the World Wide Web happens as a part of everyday life. In a job interview, you are asked to describe what happens behind the scenes when you open a web browser and enter a URL. The hiring manager wants to hear your knowledge of assembling packets of PHP, JavaScript, HTML, networking, or other technologies involved and how the sequence proceeds. What are the details of what happens behind-the-scenes?
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Continue reading “What Happens Technically when Someone Opens a Web Browser and Goes to a Website?”
Problem scenario
You have a Docker container that supports Chef or some automatic way of installing Chef. The automation is failing at the end because you are being prompted to accept a license. What should you do to be able to invoke Chef commands automatically?
Solution
With the first Chef command, e.g., “chef env”, use the “–chef-license accept” option/flag. Here is an example:
chef env –chef-license accept
For more information,
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Problem scenario
You run a pip command (e.g., pip –version), but ou get an error like this:
Traceback (most recent call last):
File “/home/mike/.local/bin/pip”, line 7, in
from pip._internal.cli.main import main
File “/home/mike/.local/lib/python3.*/site-packages/pip/_internal/cli/main.py” , line 60
sys.stderr.write(f”ERROR: {exc}”)
You no longer want to use Python 2 in on the server. What should you do?
Solution
1.a.
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Continue reading “How Do You Troubleshoot the pip Message ‘sys.stderr.write(f”ERROR: {exc}”)’?”
Problem scenario
Using a Mac computer your mouse becomes lost or you have an application that is open (based on the black dot underneath its icon), but you cannot find the application. Your computer thinks the application is open, but it is not. What should you do?
Solution
Is your laptop connected to another monitor? If an HDMI cable is connected to the laptop and that monitor is off or hidden,
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Problem scenario
You want to instantiate a class with default values if the class was called to create an object without all the settings. You want to verify you know how to code this basic object-oriented programming feature. You want to print out specific member variables of an object. How do you do this?
Solution
Use this program:
#!/bin/python3
class Computer(object):
def __init__(self, …
Problem scenario
When trying to attach a Lambda function to a VPC, you get an error like this: “The provided execution role does not have permissions to call CreateNetworkInterface on EC2”
What should you do?
Solution
1. Go to IAM and create a policy. Use the JSON editor. Use these settings (taken from StackOverflow):
{
“Version”: “2012-10-17”, …
Continue reading “How Do You Attach a Lambda Function to a VPC?”