A Technical I.T./DevOps Blog
Problem scenario
Using a web-based email that is powered by roundcube, how do you change the time zone?
Solution
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Continue reading “How Do You Change the Time Zone in a RoundCube Email Account?”
Problem scenario
List operations such as .sort() will change previous copies of the list.
String operations such as .replace(“old_pattern”, “new_pattern”, count), will not change the variable or its copies; these operations will return a string after the replace operation has run on the original string.
Why is this behavior happening?
Solution
In-place changes and mutability are factors.
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Continue reading “Why Are Python List Operations/Methods Unlike Python String Operations/Methods?”
Problem scenario
You are using Chef and the Kitchen command line tool. If a kitchen command fails, how can you find out the root cause?
Solution
With the command that fails, re-run it with this at the end: –log-level=debug
To learn more about the verbosity of kitchen commands, see this: https://docs.chef.io/workstation/ctl_kitchen/#options
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Continue reading “How Do You Troubleshoot a Kitchen Command?”
Problem scenario
You are running a Python script. You keep getting “SyntaxError: invalid syntax” and a line number. You can find nothing wrong with the syntax on the specified line number. What do you do?
Possible solution #1
Look at the line with code, as opposed to blank line(s), above it. Is there a missing quote, brace, bracket or parentheses?
Possible solution #2
Are you trying to use an “if” statement on one line?
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Continue reading “How Do You Troubleshoot “SyntaxError: invalid syntax” in Python?”
Problem scenario
You have an iCloud, iTunes, iMessage, FaceTime, or some other Apple account online. You want to cancel your account and destroy or delete the data. What do you do?
Solution
1. Log into your Apple.com account (e.g., https://appleid.apple.com/#!&page=signin).
2. Go here: https://privacy.apple.com/
3. Go to “Request to delete your account”
4.
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Problem scenario
You want to pass more than one subnet to an “aws eks” command.
You tried to delimit the list with commas (or separate two subnet IDs with commas). You received this error message:
An error occurred (InvalidParameterException) when calling the CreateNodegroup operation: The subnet ID ‘subnet-0abcd1234,subnet-zyxw9876’ does not exist (Service: AmazonEC2; Status Code: 400; Error Code: InvalidSubnetID.NotFound; Request ID: Proxy: null)
What should you do?
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Continue reading “How Do You Pass Two or More Subnets to an “aws eks” Command?”
Problem scenario
You have read about the Google Datastore and Google Firestore. But you do not know the differences. What are they?
Solution
Go here.
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Continue reading “How Does Google Datastore Compare/Contrast with Google Firestore?”
Problem scenario
You want each line of a file to have a prefix or suffix attached. How do you print out this combination of a fixed string with each individual line of the file?
Solution
cat foobar.txt | awk ‘{ print “prefix” $1 “suffix” }’ …
Continue reading “How Do You Write a Bash Command That Combines a String with Each Line of a File?”
Question
Normally when you use the man page, you just type man nameofcommand. But you have seen integer numbers between 1 and 9 (inclusive) between the “man” and the command’s name. What do those numbers signify?
Answer
This legend was taken from “man man” on a Linux server:
1 Executable programs or shell commands
2 System calls (functions provided by the kernel)
3 Library calls (functions within program libraries)
4 Special files (usually found in /dev)
5 File formats and conventions eg /etc/passwd
6 Games
7 Miscellaneous (including macro packages and conventions), …
Continue reading “What Does the Number “2” in a man Command Mean?”
Problem scenario
You have a list in Python that you copy into another variable. You change the original list and the copied version changes. Why does the copied version get copied and what can you do to overcome this?
Solution
There is something called a “deep” copy and a “shallow” copy. This program will illustrate both the problem and the solution:
list_a = [3, …
Continue reading “Why in Python Does a Variable Copy Get Changed when You Change Its Source?”