How Do You Fix a Carrier Thermostat That Is Blinking All Lights and Not Working?

Problem scenario
Your Carrier thermostat (e.g., a programmable Comfort (TM) Series Touch-n-Go (TM)) is not working. There is a glitch or apparent malfunction on the screen. All the lights flash on with the backlight turning on -- then the display goes dark (unlit with no indication). The heating and cooling does not work. The batteries seem good; the thermostat showed them at two-thirds strength (two of three bars were strong).

The display looks like this:

Carrier Thermostat Display Example

What should you do?

Possible Solution
Try with different known-good batteries. (This solution is particularly helpful if the thermostat itself is less than five years old.) The problem may seem like the original batteries are fine, but really they are defective. One Carrier thermostat manual (that comes with three different programmable thermostat models that Carrier makes) specifically say that the batteries should be replaced when there is one bar of strength left -- not when there are no bars of strength left. We recommend replacing the batteries as soon as the battery indicator light is visible that one bar of strength is gone/blank/weak and two are dark/strong. Otherwise you may have a problem as the one described above.

How Do You Troubleshoot “mount: /foobar: must be superuser to use mount” when You Open a Terminal in Linux?

Problem scenario
When you open a terminal or log into a Linux server, you see a message like this:

"mount: /foobar: must be superuser to use mount."

You suspect some bash script is running every time you log in. What should you do?

Possible solution #1
If you are running a Red Hat server, go to /etc/profile.d/. Sort the files by time modified like this:

ls -lh --sort=time

Look for a script that is trying to mount foobar.

Possible solution #2 (more of a tip to lead to a solution):
Run this command to find the directory that is attempted to be mounted:

sudo find / -name foobar

Is the directory corrupt?

Possible solution #3 (more of a tip to lead to a solution):

df -h | grep foobar

Possible solution #4 (more of a tip to lead to a solution):

cd /
sudo grep -R foobar

Confused about Legal Policies for your Small Business?

Problem scenario
You run a website business. Where do you go to get an understanding about legal policies? You want to learn more about how to comply with Amazon's Affiliate Marketing program's policies. What do you do?

Solution
You can try termly.io for general policy information assistance. For Amazon's Affiliate Marketing program specifically, see this external posting. For the FTC's guidance that was published in March of 2013, see this external posting.

How Do You Troubleshoot Errors Such as “/lib64/libcurl.so.4: no version information available”?

Problem scenario
You try to run an obs command. You get errors like these:

var/lib/snapd/snap/obs-studio/1195/usr/bin/obs: /lib64/libcurl.so.4: no version information available (required by /var/lib/snapd/snap/obs-studio/1195/usr/bin/obs)
/var/lib/snapd/snap/obs-studio/1195/usr/bin/obs: symbol lookup error: /var/lib/snapd/snap/obs-studio/1195/usr/bin/obs: undefined symbol: obs_get_module_lib

What should you do?

Solution

  1. Back up the /lib64/libcurl.so.4 to a user's home directory (just in case).
  2. Run this:
    sudo find / -name libcurl.so.4 | grep -i obs
  3. Copy one of the files found above to /lib64/

How Do You Troubleshoot Adding Red Hat Packages with Errors Like “Curl error (77): Problem with the SSL CA cert (path? access rights?)”?

Problem scenario
You try to run a DNF command, but you get stymied with errors like these:

Fedora 32 foobar (From SomeCompany) - x86_64 0.0 B/s | 0 B 00:00
Errors during downloading metadata for repository 'fedora-somecompany-foobar': - Curl error (77): Problem with the SSL CA cert (path? access rights?) for https://mirrors.fedoraproject.org/metalink?repo=fedora-somecompany-foobar-32&arch=x86_64 [error setting certificate verify locations:
CAfile: /etc/ssl/certs/ca-certificates.crt
CApath: /etc/ssl/certs]
Cannot prepare internal mirrorlist: Curl error (77): Problem with the SSL CA cert (path? access rights?)

How do you not get blocked by a problem like this?

Possible solution #1
Look at /etc/ssl/certs/ca-certificates.crt. Is it the right size? What are the permissions? Messing around with .so files and curl packages can involve accidentally deleting this file. Where can you one that you need? Run this: sudo find / -name ca-certificates.crt
Another valid one may be somewhere else on your machine.

Possible solution #2
Try to run the dnf command with sudo or as root.

Possible solution #3
Run this command (but substitute "somecompany-foobar" with what you saw in the original error message):
sudo dnf config-manager --set-disabled fedora-somecompany-foobar
Now try to run the command again.

Possible solution #4
Run a command like this:
sudo dnf -y install ca-certificates

How Do You Fix a White/Blank Web Page?

Problem scenario
You have a white screen in the web browser. Why is the website just white when using HTML?

Possible Solution #1
Are the font and background color the same? If the font is set to be white, that may be the problem. HTML has hexadecimal codes for the font and background color; you can view them here: https://htmlcolorcodes.com/

Possible Solution #2
Is there a misspelling in the URL and the ultimate web page? You may want to check the .html file's name on the back-end.

Possible Solution #3
Has the content been accidentally commented out? Is there a formatting issue or syntax problem with the HTML file itself?

Possible Solution #4
If you are using PHP, see this posting: How Do You Fix a PHP Web Page when the Page Is Completely Blank?

Possible Solution #5
Scroll down to the very bottom. The page may be very long and have content at the bottom.

Is There a Difference between an IAM Role and an IAM Access Key?

Question
Is there a difference between an IAM role and an IAM access key?

Answer
Yes. To summarize this article, IAM users are for humans and IAM roles are for AWS components (such as S3 buckets and EC-2 instances). As a less significant difference, you do not rotate IAM roles (according to this medium.com post).

An access key is like a username; it will need a secret key that is associated with it for authentication.

An IAM role associates a service in AWS (e.g., an EC-2 instance) with authorization to access various other services (e.g., S3 buckets). For typical AWS administration there would be no password associated with an IAM role. An access key would have a secret access key ID that would be needed to authenticate a user (e.g., to run some AWS CLI commands).

To learn about the difference between IAM keys and IAM roles, read this article and see this video.

(IAM keys are AWS access keys. We know this because "[a]ccess keys are long-term credentials for an IAM user or the AWS account root user." (The quote was taken from this Amazon page.)

Access keys consist of two parts: an access key ID (for example, AKIAIOSFODNN7EXAMPLE) and a secret access key (for example, wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY).

https://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_access-keys.html

What Does MSK Stand For in I.T./DevOps?

Question
You have seen "MSK" in an article on the public cloud. Does the "K" stand for "Key"? What does MSK stand for?

Answer
MSK stands for "Managed Streaming for Kafka". It is an Amazon product.

"Amazon Managed Streaming for Apache Kafka (Amazon MSK) is a fully managed service that enables you to build and run applications that use Apache Kafka to process streaming data. Amazon MSK provides the control-plane operations, such as those for creating, updating, and deleting clusters." (Taken from https://docs.aws.amazon.com/msk/latest/developerguide/what-is-msk.html.)

How Do You Get the Voicemail Indicator Icon to Work on an Android Phone?

Problem scenario
You are using an Android phone. When you get new voicemails, there is no indication. What should you do?

Possible solution
Go to the settings in your phone (possibly through a sprocket/gear symbol). Go to Apps -> Voicemail. Click on "Force stop" in the lower right hand corner. Allow it to stop. Then click "Open." This may work.

What Can Cause an Application to Run Slowly?

Problem scenario
You support an existing application and its servers. It is experiencing slowness as the users are complaining about its performance. What are some potential root causes of this slowness?

Possible Solutions

  • The slowness is caused by the client. A user's workstation has something wrong with it (e.g., malware, or it is trying to run too many applications at once).
  • Network congestion between the client and the server.
  • The server's disk IO activity, CPU activity or RAM utilization is too high.
  • Overloaded application; there is a spike in application's demand (e.g., a temporal business reason is causing the application to be heavily utilized beyond normal conditions). Scaling horizontally with load balancers could help remedy this.
  • There is a DNS configuration issue. DNS cacheing and or new misconfigurations can cause an application to be slow.
  • A change to a load balancer (e.g., HAProxy, an F5 load balancer or an AWS application load balancer) introduced a misconfiguration which is potentially causing the slowness.
  • There could be a denial of service attack. Malware or hackers could be the culprit.
  • If the server was moved, there may be a lack of caching. Some web server accelerators could have been the basis of a highly performant server. A sever being in a new geographic location could put it in a suboptimal region for the users.
  • A relevant database tier could have a backup routine, stored procedure or other maintenance job could be running. Was there an email about an outage? Poorly crafted SQL statements can cause problems. For tips on tuning a relational database, see this posting.
  • Check the logs of the application and other components. There may be something obvious.