A Technical I.T./DevOps Blog
Problem scenario
You run a grep command but it fails. You get a message about “memory exhausted.” What should you do?
Solution
Possible Solution #1
If you are comparing two files line-by-line, try reversing the order of the file arguments for the grep command. For example try these two versions:
grep -f a.txt b.txt
grep -f b.txt a.txt
If the file in the left argument is smaller,
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Continue reading “How Do You Fix the Error “grep: memory exhausted”?”
Terraform: Up & Running: Writing Infrastructure as Code by O’Reilly Media
Terraform Cookbook: Efficiently define, launch, and manage Infrastructure as Code across various cloud platforms by Packt Publishing
Infrastructure as Code: Managing Servers in the Cloud by O’Reilly Media
Learning DevOps: The complete guide to accelerate collaboration with Jenkins, Kubernetes, Terraform and Azure DevOps by Packt Publishing
Terraform: Up and Running: Writing Infrastructure as Code by O’Reilly Media
HashiCorp Certified: Terraform Associate Practice Test
The Terraform Book by Turnbull Press
Problem scenario
You are running Vagrant to create a VM on Oracle VirtualBox. You are given a prompt after your “vagrant up” command:
“Which interface should the network bridge to?”
No option seems to work. You have used a variety of different names, GUIDs, syntaxes, etc. What should you do?
Solution
Use “1)” or “2)” or any of the integer values listed above the question.
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Question
What is the “watch mechanism” in Kubernetes?
Solution
A notification system from the API server to trigger changes in Kubernetes. In Kubernetes there are observable events. The watch mechanism is a system for listening for specific events to respond to. The Kubelet, the Scheduler, the kube-dns pod, and individual controllers are components that use the watch mechanism. The API server is a central component that watching components are aware of.
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Continue reading “What Is The Watch Mechanism in Kubernetes?”
Problem scenario
You try to run a pipenv command, but you get an error about “tomlkit.exception”.
Solution
Copy the Pipfile to a new name (to back it up). Delete the original Pipfile. Try to run the command again. If it still fails, try removing pipenv by uninstalling it. Then reinstall pipenv. Then reboot the computer.
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Continue reading “How Do You Troubleshoot the pipenv error message “tomlkit.exception”?”
Problem scenario
You want to install and configure Apache Camel from source on any distribution of Linux. What do you do?
Solution
You cannot. But there is a way to use Apache Camel as a test.
Background: It is not something that is can be purely installed-and-configured like other applications. Camel is a framework for integrating messaging solutions or microservice architecture.
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Continue reading “How Do You Install and Configure Apache Camel on a Linux Server?”
Problem scenario
You have installed sqlite3. It is a version above 3.22.0. But when you run “make deps” you see this error message:
checking for SQLITE… no
configure: error: Package requirements (sqlite3 = 3.22.0) were not met:
No package ‘sqlite3’ found
What should you do?
Solution
Run this:
sudo apt -y install libsqlite3-dev
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Problem scenario
You have run start-dfs.sh and start-yarn.sh. You have stopped all the Hadoop services too. When you run “jps”, the NameNode is not showing up. You have tried a variety of different troubleshooting methods (including rebooting the NameNode). The NameNode has never worked correctly. You can delete all the data in the cluster because it never really worked. What should you do?
Solution
Run this but remember it will delete all your data:
hdfs namenode -format # Warning: this command will delete all your data in Hadoop …
Continue reading “How Do You Get the NameNode Process to Start in Hadoop?”
Problem scenario
You have added a partition to Linux. When you type “df -h” you do not see evidence that it is available. You tried the “sudo lsblk” command, but you do not see the device. The “fdisk -l” command does show the new device and the size that is available. The command ll /dev/sd* does not show your new device.
When you run “fdisk /dev/sdaX”, you get this: “fdisk: cannot open /dev/sdaX: No such file or directory”
How do you make it available?
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Problem scenario
You are aware that arrays are a supported data type in Bash. You would like to iterate through some variables as arrays could enable complex logic. What do you do?
Solution
The array is zero-based. So the first element is referred to by index number 0.
continualarray=(dog cat hamster rabbit horse cow)
echo ${continualarray[2]}
echo ${continualarray[5]}
Create a file foobar.txt to test an array’s line-reading capacity.
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