A Technical I.T./DevOps Blog
Problem scenario
You are not sure if an email address is associated with spam. Someone make comments on your blog. You are not sure if they are legitimate comments or if it is someone trying to spam a website or create a message that is an advertisement. What should you do to check-in on the email address?
Solution
Try https://cleantalk.org/blacklists/
On cleantalk.org you can search for IP addresses, email addresses, or domains (FQDNs of a URL).
Problem scenario
You have a file that is too big to fit into memory. How can Python read the file?
Possible Solution #1
You can use the "open" method and the "read()" or "readlines()" methods. Avoid using read() because that will read the entire file into memory. The readline() and readlines() methods can be given a byte number as an argument. They will retrieve only a portion of the file. Alternatively the file can be processed in a for loop line-by-line.
For more information on the implementation, see these postings:
https://www.w3schools.com/python/ref_file_readline.asp
https://www.w3schools.com/python/ref_file_readlines.asp
https://www.journaldev.com/14408/python-read-file-open-write-delete-copy
Possible Solution #2
Add memory to your system. If you need assistance, see this posting.
Problem Scenario
You run an HDFS command, but you get this message: "ERROR: Hadoop common not found"
What should you do?
Solution
As the hduser or user that runs hdfs, log in. Run echo $HADOOP_HOME
That directory should have a libexec directory with a file called hadoop-config.sh.
Run this: ls -lh $HADOOP_HOME/libexec
One way to create it is this: 1) find a hadoop-config.sh file (e.g., with a sudo find / -name hdfs-config.sh command). 2) run this command sudo ln -s /path/to/hdfs-config.sh $HADOOP_HOME/libexec/hadoop-config.sh
Be mindful of the "hadoop-config.sh" and "hdfs-config.sh" difference; it is subtle.
Problem scenario
You find a showerhead with black build-up or gunk. You want the spouts to be clean. It may look like this:
You want to remove the black flecks from inside. What should you do to clean the inside of the showerhead?
Solution
1. Get a dishwashing brush, a bottle brush, or a toothbrush with long bristles.
2. Get some bleach.
3. Pour the bleach on the bristles of the brush.
4. Brush inside to get the black stuff out of the showerhead.
Problem scenario
You know how to find the individual postings. You know how to find the main pages in WordPress. But how do you find your advertisers and sidebars on your site (to edit them)?
Solution
In WordPress, go to Appearance -> Themes. Choose the theme that applies to your site. On the main part of the screen, click/browse to the area of your site that has the blocks, columns, sidebars and/or advertisements. On the left click on "Widgets."
Question
Variables in Java store data (e.g., a string or number). How is instantiation of a variable different from initialization, or are they the same?
Answer
Instantiation is different from initialization. Instantiation is the creation of the variable (e.g., through the Java syntax or invocation of a method that creates the variable). A class can be instantiated or a primitive variable can be instantiated. Instantiation involves memory allication for the object (either for a class or a primitive value). See Oracle documentation and TechTarget's definition.
Initializing a variable is the act of giving a variable a specific value. When a variable is assign an initial value, this is initialization.
"Variables are containers for storing data values." (Taken from https://www.w3schools.com/java/java_variables.asp)
Instantiation and initialization are terms used outside of Java.
Question
The Declaration of Independence says "A Prince whose character is thus marked by every act which may define a Tyrant, is unfit to be the ruler of a free people."
Who was the prince?
Answer
It was the King of Great Britain and Ireland, George III.
As far as the Continental Congress was concerned, George was no longer its king. Instead, the Declaration of Independence outlined 27 grievances against George and labeled him “a Tyrant […] unfit to be the ruler of a free people.
https://www.nationalgeographic.com/history/article/king-george-iii-american-revolution
He would be the last king of America.
Problem scenario
You must record an audible greeting for a voicemail. You do not want to use your voice. What should you do?
Solution
1. Go to this website: https://wideo.co/text-to-speech/.
2. Enter this text (but substitute 212-123-4567 with your phone number:
Hello, you have reached 2,1,2,1,2,3,4,5,6,7. No one is available to take your call, please leave your message after the tone.
3. Choose the voice in the drop down as desired. Listen to the preview. Have your phone listen to the greeting when you record your own greeting.
Problem scenario
You have been reading The Declaration of Independence: The Evolution of the Text by Julian P. Boyd. The color photographs of the drafts of the Declaration of Independence show a brown ink. Why did Thomas Jefferson choose a brown ink?
Solution
He did not use brown ink; he used black ink. Over time with air, the color of the writing turns to a brownish appearance on the original pages (according to the introduction of American Scripture: Making the Declaration of Independence by Pauline Maier).
Problem scenario
You received an email that you should not have. The footer requests you let the sender know and delete the copy you received. What should you do?
Solution
We think you should not examine the contents closely, delete the email and let the sender know. There may be a disclaimer boilerplate in the email that may or may not have legal weight. Even if there is no such disclaimer on this accidental email, you will be proud that you respected the confidentiality and privacy of another party. Treating other people as you would like to be treated can give you moral high ground. Being polite and sensitive can help you in the long run. Forwarding it on or disclosing the contents of the email may be bad manners.
It is advisable to have in your long-term memory a disposition to honoring commitments to the privacy of others. Mistakes happen.
For more information, and some mixed treatment, about such email footer disclosures, see this.