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.
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
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?
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.
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?
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.
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” }’ » Read more..
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), » Read more..
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, » Read more..
Problem scenario
You want to use the copy feature in Python. What do you do?
Solution
To see the different types of copying, use a mutable object such as a list. Here is an example:
import copy
var1 = [1, 2, 3, 4]
shallow_copy = var1
deep_copy = copy.deepcopy(var1)
var1.append(999999999999)
print()
print(shallow_copy)
print(” — Shallow copy above and deep copy below —.”)
print(deep_copy)
For most (or perhaps all) intents and purposes,