A Technical I.T./DevOps Blog
Question
What does SLI and SLO stand for?
Answer
SLI is an initialism for Service Level Indicator. SLO is an initialism for Service Level Objective.
A Service Level Indicator is a metric of service such as query-per-second, megabytes per second, transactions per minute, HTTP requests per minute etc. These are quantifiable measurements of some I.T. service. SLIs, among other things, are the metrics of a monitoring system.
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Problem scenario
You have a camera (e.g., a TCP/IP ADT security camera) attached to your a router on the network with your laptop. You know the camera’s MAC address by looking at the back of the camera itself (or you know its IP address on your network which is even more helpful). How do you use this camera over the network?
Solution
1.
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Continue reading “How Do You Configure the Wireless Security Camera with a TCP/IP Network?”
Problem scenario
You inherited a GitLab server on your network to manage. You want to find the front end of the URL. What should you do?
Solution
Find the external IP address. Log into the back-end. If it has access to the internet, run this command: curl icanhazip.com
If you have no access to the internet, run this command: ip addr show
Use the IP addresses exhaustively in a web browser with a port in this fashion (where ppp should be replaced with the port number you want to try): http://x.x.x.x:pppp
The port number may be one to five numbers long.
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Continue reading “How Do You Find the Web UI of a GitLab Server on Your Network?”
Problem scenario
You run this command: sudo ls -lh /dev
You see output like this:
crw-rw—- 1 root tty 7, 131 Dec 23 19:20 vcsa3
crw-rw—- 1 root tty 7, 132 Dec 23 19:20 vcsa4
crw-rw—- 1 root tty 7, 133 Dec 23 19:20 vcsa5
crw-rw—- 1 root tty 7, 134 Dec 23 19:20 vcsa6
You want to know if the “c” is a link to another file or something else.
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Continue reading “What Type of Linux File Has Permissions That Are Symbolized with a “c”?”
Problem scenario
When in virtualenv you try to run a Molecule command. But you get this message:
ERROR: Unable to contact the Docker daemon. Please refer to https://docs.docker.com/config/daemon/ for managing the daemon
What should you do?
Solution
1. Exit virtualenv. Run this command: deactivate
2. Go back into virtualenv (e.g., run a command like this source my_env/bin/activate).
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Problem scenario
You have a .js file on your desktop or on a web server. You want to have the code execute and present itself nicely (not just see the raw code) in a web browser. How do you do this?
Solution
You must use the .html extension. You must have
<html</html
tags. Here is an example. Name this file contint.html and place it on your desktop,
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Continue reading “How Do You Get JavaScript to Present in a Web Browser?”
Problem scenario
You want to substitute the nth word of a given line. How do you use awk to accomplish this?
Solution
Let’s assume the lines that you want to modify are in goodfile.txt. To replace the fourth item in the string with “new string”, run this command:
cat goodfile.txt | awk ‘{ print $1 ” ” $2 ” ” $3 ” new string ” $5 ” ” $6 }’
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Problem scenario
You want to run a Java program via a .jar file. You want to invoke it like this java -jar nameOf.jar
What do you do?
Solution
1. Install Maven. If you need assistance, see this posting.
2. Follow these directions.
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Continue reading “How Do You Create a .jar File for Your Java Program?”
You have one of the following two problems:
Problem scenario #1
Your GCP startup-script is not working. You do not know why. What should you do?
OR
Problem scenario #2
A bash script is not working. It stops executing after a certain line. There are few clues as to what is wrong.
Solution
Did you copy the script from a webpage?
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Continue reading “How Do You Troubleshoot a Bash Script Copied from the Internet?”
Question
Why did Apple call one of their computers the Macintosh?
Answer
It was based on a type of apple that you eat (e.g., golden delicious, Fuji, etc.). It would have been called the McIntosh, but there were legal reasons for adding the letter “a”. To read more about how the name was chosen, see this page.
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Continue reading “Why Did Apple Call One of Their Computers Macintosh?”