A Technical I.T./DevOps Blog
Problem scenario
You want to listen to a .WAV (or an .mp3) file on your Ubuntu/Debian/Linux Mint machine from the command line. What should you do?
Solution
Run this: sudo apt -y install sox
Run this (but substitute “/play/to” with the path to your file and replace “nameof.wav” with the name of the file you want to listen to): play /path/to/nameof.wav
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Continue reading “How Do You Play a .WAV File Using Ubuntu?”
Question
The terms provisioner and provider seem similar. How would one be compared versus the other? Are provisioners and providers in Terraform the same? If not, how are they different?
Answer
Provisioners in Terraform run commands and do various things to a given server (e.g., transfer a file, run a shell command, run chef-client commands). (This was taken from page 213 of Terraform: Up &
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Continue reading “How Are Provisioners Different from Providers in Terraform?”
Question
Attention to details such as terminology can be important in technical writing. When making software, should you use the term build, create, develop, grow, produce or write?
Answer
We think that context matters. It seems that the terms write or build are often ideal when you are describing the process for creating/producing a software product, application or “work.”
Richard Stallman said ‘I think it is ok for authors (please let’s not call them “creators”,
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Continue reading “Do You Build, Create, Develop, Grow, Produce or Write software?”
Question
You have heard the term “white box computer.” What is it?
Answer
A workstation or server that is not created by a well-recognized brand. Some people refer to plain flavors as “vanilla.” If a data center is getting white-box servers, they are not getting Dell or HP servers. White-box servers are affordable and may compete with the public cloud. Commodity servers are well known for being acceptable for Hadoop.
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Problem scenario
You run a terraform command. You get ‘unsupported argument aws_key_pair’. You want terraform to create an EC-2 server with a specific key pair. What should you do?
Solution
Don’t use “aws_key_pair”, use “key_name”. The aws_instance section in a .tf file uses a different keyword. (The aws_key_pair is for creating an key-pair in AWS.) Use the “key_name” field for aws_instances like this:
resource “aws_instance” “example” {
ami = “ami-01a1234abcd567”
instance_type = “t2.micro”
key_name = “appleorange”
} …
Continue reading “How Do You Troubleshoot the Terraform Error ‘unsupported argument aws_key_pair’?”
Question
You have read that CI is different from CD. How are they different (CI vs. CD)?
Answer
CI, continual integration involves integrating code from two or more developers on a continual (regular or ongoing) basis. CD (with the “C” standing for continuous or continual) can refer to delivery (with a manual process into production) or deployment (an automatic process even to production)*.
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Question
Some companies are getting away from VPNs in favor of zero trust systems. It can help save money on bandwidth and facilitate a better network performance when every employee is working remotely. Are NoVPN Services More Secure for a Given Enterprise? Is it recommended to use non-VPN services?
Answer
We think this is a debatable whether VPNs (Virtual Private Networks) make systems more secure.
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Continue reading “Are Zero Trust Networks More Secure than VPN-Protected Networks?”
Problem scenario
You are installing CentOS 8.x but when you click on the “Installation Source” tab, nothing happens. You do not see an option to enter an installation source.
You cannot click “Begin installation.” What do you do?
Solution
Try different installation media. If you are using a boot.iso, this problem may happen.
Some DVD isos are here: http://ftp.hosteurope.de/mirror/centos.org/8/isos/x86_64/
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Problem scenario
You are using WordPress for you website. You have code that has an indentation of one to three spaces that you do not want. You did not intend for this indentation. It is usually just one line — the top line.
Here is an example:
How can you eliminate this indentation of your code?
Solution
Root cause
If you have a new line in the paragraph,
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Continue reading “How Do You Eliminate Unintended Indentation in Code?”
Question
It seems like “global” and “nonlocal” would be the same thing. How are these keywords different in Python?
Answer
Variables inside a function are local by default; variables outside of functions are global by default. (This was taken from https://www.programiz.com/python-programming/global-keyword.) This answer/article addresses the “LEGB lexical scoping rule” (taken from page 872 of Learning Python).
The “nonlocal” keyword has two requirements that “global” does not have: 1) “nonlocal” must be enclosed in a function within a function;
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Continue reading “What is the Difference between global and nonlocal in Python?”