How Do You Troubleshoot the Cargo Problem “error[E0658]: use of unstable library feature ‘str_strip’: newly added”?

Problem scenario
You run a cargo command. You get this error:

error[E0658]: use of unstable library feature ‘str_strip’: newly added
69 | / construct_fixed_hash! {
70 | | /// Bloom hash type with 256 bytes (2048 bits) size.
71 | | pub struct Bloom(BLOOM_SIZE);
72 | | }
| |_^
= note: see issue #67302 for more information
= note: this error originates in a macro (in Nightly builds,

 » Read more..

Using a Debian/Ubuntu Distribution of Linux, How Do You Install kubeadm, kubectl, and/or kubelet?

Problem scenario
Using a Debian/Ubuntu distribution of Linux, how do you install kubeadm, kubectl, and/or kubelet?

You want to install kubeadm, kubectl or kubelet (without retrieving the binary of the file from a website and do a regular installation). What do you do?

Here is another way to install kubectl, kubelet and kubeadm:

curl -s | sudo apt-key add
sudo apt-add-repository “deb kubernetes-xenial main”
sudo apt-get -y install kubeadm kubelet kubectl

(If you can download a file from the internet and want to avoid using apt commands,

 » Read more..

How Do You Find the Menu Option, Button or Feature for an Application in MacOS?

Problem scenario
You are using a familiar application on a Mac. You cannot find a basic command button or menu option. What should you do?

At the very top of your screen, outside of the application itself, there is a ribbon. There should be drop down menu options specific for the application.

We find that some problems are caused because of time pressure.

 » Read more..

How Do You Get Both MapReduce Jobs and hadoop CLI Commands to Work Simultaneously without Alternately Changing an XML File Before Each One?

Problem scenario
Hadoop is not working correctly. You can get either a mapreduce job to work or a “hadoop” CLI command to work. But neither work unless you change an .XML file in between each operation.

Map Reduce jobs, when they are failing (and the Hadoop commands are working), there may be an error like this:

2021-01-01 22:47:42,337 INFO mapreduce.Job: Task Id : attempt_1609558624072_0001_m_000003_1,

 » Read more..

How Do You Solve “Could not find foobar in any of the sources” after a bundle Command?

Problem scenario
You run a bundle command (e.g., bundle exec foobar create). It fails with an error such as “Could not find foobar in any of the sources”.

What should you do?

Remove the relevant Gemfile.lock file (e.g., in the directory you are running bundle) if you are allowed to. Are you using a variety of bundle commands?

 » Read more..

What Does the “^” Operator in Python Do?

Problem scenario
In Python you try operations like these two:

5 ^ 6
9 ^ 10

Both return “3”. Why is this?

The exclusive or (aka XOR) symbol “^” “copies the bit if it is set in one operand but not both.” (Taken from

Here are some integers with their binary representation one space away:

3 11

5 101
6 110

9 1001
10 1010

5 is represented as 101.

 » Read more..

How Do You Connect over Port 5986 on a Windows Server?

Problem scenario
Port 5986 is blocked from your Linux server to your Windows server. You have used the nmap command and see that it is filtered. You believe there are no intermediate firewalls or OS firewalls blocking this port. What should you do?

This assumes you have no firewall blocking port 5986 for incoming connections to the Windows server. nmap will report 5986 is filtered despite there being nothing blocking this port if wsman’s listener has not been properly configured.*

  1. Run this script on the Windows server:

$hostName = $env:COMPUTERNAME
$serverCert = New-SelfSignedCertificate -CertStoreLocation Cert:\LocalMachine\My -DnsName $hostName
Export-Certificate -Cert $serverCert -FilePath c:\vagrant\PsRemoting-Cert1.cer
Get-ChildItem c:\vagrant\PsRemoting-Cert1.cer
Enable-PSRemoting -Force
New-Item -Path WSMan:\localhost\Listener\ -Transport HTTPS -Address * -CertificateThumbPrint $serverCert.Thumbprint -Force

  1. That is it.

 » Read more..

How to Install Incubed (in3) for Bash?

Problem scenario
You want to do Blockchain development with Ethereum using Bash. How do you install Incubed (in3) for Bash on a Debian distribution of Linux (such as Ubuntu or Linux Mint)?

Run these commands:

sudo apt -y update
sudo apt-get -y install software-properties-common
sudo add-apt-repository ppa:devops-slock-it/in3
sudo apt -y install jq in3 in3-dev  » Read more..

How Do You Troubleshoot the AWS Error “Subnets specified must be in at least two different AZs”?

Problem scenario
You run an AWS CLI command, but you get this error message:
“An error occurred (InvalidParameterException) when calling the CreateCluster operation: Subnets specified must be in at least two different AZs”
How do you find subnets in different availability zones?

Run commands such as these (but replace the “us-west-x” and “us-east-x” with the availability zones that you use):

aws ec2 describe-subnets –query ‘Subnets[?AvailabilityZone==us-west-1a]’
aws ec2 describe-subnets –query ‘Subnets[?AvailabilityZone==us-west-1b]’
aws ec2 describe-subnets –query ‘Subnets[?AvailabilityZone==us-west-1c]’
aws ec2 describe-subnets –query ‘Subnets[?AvailabilityZone==us-east-2a]’
aws ec2 describe-subnets –query ‘Subnets[?AvailabilityZone==us-east-2b]’
aws ec2 describe-subnets –query ‘Subnets[?AvailabilityZone==us-east-2c]’

Now you will see more subnet IDs for your original command.

 » Read more..

How Can a Base Branch Not Be a Master Branch in Git?

Problem scenario
You have seen the term “base branch” in Git documentation. How can it not be the main branch?

In the context of a Pull Request, where one branch’s changes will update the same files (if any exist) and any new files will be copied into another branch, the branch receiving the changes and/or files is the base branch.

 » Read more..