A Technical I.T./DevOps Blog
Problem scenario
You are trying to update a SQL table with a SQL statement (using the “UPDATE” keyword). You keep getting “ERROR: syntax error at or near” with a reference of the value you are trying to give to a cell in a row in a SQL table. You verified you have no extra commas, apostrophes, or semicolons in your SQL UPDATE statement. You verified that the columns exist in the table and are spelled correctly in your UPDATE statement.
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Problem scenario
Your remote control to the car alarm (aka key fob) is not working reliably. You need to get into your car or at least disarm the the alarm on-demand. How do you get the keyless entry device (or the alarm remote control or key fob) to work reliably to it will deactivate or activate the alarm when you need it to happen?
Solution
Possible solution #1
Tighten the screws in the back or the side.
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Continue reading “How Do You Troubleshoot a Car Alarm Remote Control Device (aka Key Fob)?”
Problem scenario
You created a Windows server in GCP. How do you obtain credentials and connect to it?
Solution
1. Make sure the firewalls allow for the connection. See this posting if you need to change that.
2. In the GCP console, go to Computer Engine -> VM Instances.
3. Go to the VM you want to connect to.
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Continue reading “How Do You Log into a Windows Server in Google Cloud Platform?”
Problem scenario
You are running a LAPP application on Ubuntu Linux with PostgreSQL. A user has complained that she cannot log into your Postgres database via a LAPP application. You are not sure if the attempts are even registering of if the user is entering an incorrect username. How do you look at a log to see a history of unsuccessful attempts at logging into the Postgresql database?
Solution
Examine this file: /var/log/postgresql/postgresql-x.y-main.log
(Substitute x.y with the major and minor versions of PostgreSQL you are running e.g.,
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Continue reading “How Do You View Failed User Login Attempts to a PostgreSQL Instance?”
Problem scenario
You have a PowerShell script that you want to be able to detect the hard drive letter it resides on. How can PowerShell detect the hard drive letter that the .ps1 file itself is stored on?
Solution
Use this command: (get-location).drive.name
To get the drive letter to be in a variable named $dl, use this:
$dl = (get-location).drive.name
Now you can use $dl as the drive letter in the PowerShell script.
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Problem scenario
In Windows 7 you start (or launch) HeidiSQL. You try to connect to a remote server but you get the error “Cannot find a usable libpq.dll. Please launch heidisql64.r5168.exe from the directory where you have installed it.” How do you solve this problem?
Solution
Uninstall HeidiSQL and install the latest one from here. If you download the latest build,
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Problem scenario
You have a LAMP (or LAPP) web page application. The PHP code uses the session() functionality. Once a user logs in successfully, he/she can browse to successive web pages. You want to at least allow the user the opportunity to destroy the session (and terminate the authentication session). How do you do this?
Solution
#1 Modify the .php file that you want to have the logout feature.
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Continue reading “How Do You Create an Option to Logout for a PHP Web Page to Destroy the Session?”
Problem scenario
You know Scala is installed because you use “man scala” and see the correct man page. But when you try to find the version, you get an error. Specifically you run this command: scala version
You see this: “No such file or class on classpath: version.” How do you find out what version of Scala you have installed?
Solution
Reboot the server.
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Continue reading “How Do You Troubleshoot the Scala Error “No such file or class on class path”?”
Problem scenario
You are running Ubuntu Linux in AWS. You want to install R. How do you do this?
Solution
(These directions below were adapted from this link.)
Prerequisite
Verify you have 1 GB of RAM. Run this command: sudo dmidecode -t 17 | grep Size
If you see 512 MB in the results of the above command,
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Continue reading “How Do You Install R on an Ubuntu Linux Instance of AWS?”
Problem scenario
You want to install Scala to an Ubuntu instance of AWS. How do you do this?
Solution
Prerequisite
Verify you have 1 GB of RAM. Run this command: sudo dmidecode -t 17 | grep Size
If you see 512 MB in the output, then you will not be able to get Scala installed. You will need an AWS instance with a flavor that has 1 GB of RAM or more.
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Continue reading “How Do You Install Scala on an Ubuntu Instance of AWS?”