A Technical I.T./DevOps Blog
You scanned some documents into a Windows machine. One or both of the following apply:
Problem scenario #1
When you right click on them to print them, the print preview is showing them rotated 90 degrees from the orientation you want.
Problem scenario #2
When you right click on them to print them, they print rotated 90 degrees from the orientation that you would prefer.
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Problem scenario
You try this prog1.py:
book = {}
book[”apple”] = 5
var1 = book[”orange”]
It returns this:
Traceback (most recent call last):
File “prog1.py”, line 3, in
var1 = book[“orange”]
KeyError: ‘orange’
You often see a couple lines of code check if a key exists in a dictionary before a specific action. You want to avoid this and write Python in a more elegant fashion.
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Continue reading “In Python How Do You Avoid the Inelegant Dictionary Key-Check Logic?”
Question
You have heard of different stacks such as the call, kernel and user stacks.
How are they different?
Answer
“The call stack, or runtime stack, is an area of memory used to store function return information and local variables.” (This was taken from https://developer.arm.com/documentation/101470/2021-2/Examining-the-Target/Examining-the-call-stack)
“The user stack contains the arguments, local variables, and other data for functions executing in user mode.” (Taken from https://www.gotothings.com/unix/user-and-kernel-stack-for-copy-program.htm.)
“The user stack is only used while the process is running in user mode.” (Taken from https://www.baeldung.com/linux/kernel-stack-and-user-space-stack.)
“The kernel stack is a per-process memory region maintained in kernel memory that is used as the stack for execution of the functions called internally during the execution of a system call.” (This was taken from page 122 of Kerrisk’s The Linux Programming Interface book.)
The user stack resides in a different location from the kernel stack (taken from https://stackoverflow.com/questions/12911841/kernel-stack-and-user-space-stack).
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Continue reading “What Is the Call Stack, the Kernel Stack and the User Stack?”
Question
You have read about user mode and kernel mode. Are they the different from userspace and kernel space respectively?
Answer
Yes. User space is not the same as user mode. Kernel space is not the same as kernel mode.
“Modern processor architectures typically allow the CPU to operate in at least two different modes: user mode and kernel mode (sometimes also referred to as supervisor mode).” Taken from page 23 of The Linux Programming Interface by Michael Kerrisk.
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Question
What is user space and is it different from the user stack? If the user stack is part of the user space, what else does user space have besides the user stack?
Answer
User space is a portion of memory of an Operating Systems that is not designated for kernel space. System calls enable user processes to enter kernel space.
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Continue reading “What Is User Space and Is It Different from the User Stack?”
Question
What is kernel space and is it different from the kernel stack?
Answer
“System memory in Linux can be divided into two distinct regions: kernel space and user space. Kernel space is where the kernel (i.e., the core of the operating system) executes (i.e., runs) and provides its services. “
Kernel space is mutually exclusive with user space (according to https://unix.stackexchange.com/questions/87625/what-is-difference-between-user-space-and-kernel-space,
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Continue reading “What Is Kernel Space and Is It Different from the Kernel Stack?”
Question
VMware makes vRealize Orchestrator and vRealization Automation. How are these products different?
Answer
vRealize Orchestrator does automation (with JavaScript, third party plugins etc.) and vRealize Automation provides a service catalog, governance policies, utilization tracking, networking, security and application services. It almost would have made more sense if they swapped names.
To learn more, see this:
https://www.youtube.com/watch?v=tLl9BzvVlLs …
Continue reading “What is the Difference between vRealize Automation and vRealize Orchestrator?”
A significant amount of cryptocurrency does not change hands after it is purchased. To read more, see this external posting.
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Continue reading “The Buy and Hold Strategy for Cryptocurrency”
Problem scenario
You are running an SSH git command (to interact with GitLab, GitHub or some Git repository), but you get “No such host is known” message. What should you do to troubleshoot this problem?
Possible Solution #1
Use “git clone git@gitserver.acme.com” (instead of “ssh git@gitserver.acme.com”; you need to use the git command first).
Possible Solution #2
Try to ping gitserver.acme.com.
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Continue reading “How Do You Solve a “No such host is known” Problem with Git Commands?”
Question
In networking, you have read about latency and jitter. How are the two terms different?
Answer
“Jitter is used to describe the amount of inconsistency in latency across the network, while latency measures the time it takes for data to reach its destination and ultimately make a round trip.” Taken from https://www.networkmanagementsoftware.com/jitter-vs-latency/.
Clock jitter can create logging discrepancies;
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Continue reading “How Is Jitter Different from Latency in Networking?”