Category: Software

Declaring, Exporting, and Reading Dynamic Variables in Bash

Posted on by rchapin

If you want to dynamically define and export variable names in Bash here is the TLDR;

# Define the name of the variable
key="my-dynamic-var-name"

# Declare it and export it
declare -gx "$key"="some-value"

To then access that value via a dynamically generated variable name

# Create a variable that contains the variable name
var_to_access="my-dynamic-var-name"

# Read the value
my_var_value=${!var_to_access}

Read the man page for declare for more details and read this article for a really good explanation and further examples.→ Continue reading “Declaring, Exporting, and Reading Dynamic Variables in Bash”

[SOLVED] ‘Virtualized Intel VT-x/EPT is not supported on this platform. Continue without virtualized Intel VT-x/EPT’ on Windows 11 host

Posted on by rchapin

I was trying to run a Debian, Linux, guest on a Windows 11 Enterprise host with virtualization enabled for the VMWare Linux guest so that I could install minikube. Minikube requires running a VM on the host on which minikube is running, so essentially, a VM within a VM.

After enabling the “Virtualize Intel VT-x/EPT or AMD-V/RVI” setting and attempting to boot the VM it indicated that this configuration was not supported on this platform.

After quite a bit of → Continue reading “[SOLVED] ‘Virtualized Intel VT-x/EPT is not supported on this platform. Continue without virtualized Intel VT-x/EPT’ on Windows 11 host”

How to check if a file is sourced in Bash

Posted on by rchapin

Sometimes you will want to ensure that a file is sourced instead of executed. This ensures, among other things, that any environment variables that the script defines remain in your current shell after the script completes.

To do so, use the following to check whether the file was sourced or run in a sub-shell

(return 0 2/dev/null) && sourced=1 || sourced=0
echo "sourced=$sourced"

Bash allows return statements only from functions and in a scripts top level scope IF it → Continue reading “How to check if a file is sourced in Bash”

Pruning directories from find

Posted on by rchapin

I have no idea why, but for some reason I always have a hard time remembering the exact syntax for find when I want to prune some list of directories from a search.

Let’s say that you want to execute a find in a directory where there are a lot of .git directories and you don’t want to search through the guts of the repo directories. With the following command we specify the prune predicate ahead of the search for → Continue reading “Pruning directories from find”

Using cut with a delimiter of any amount of whitespace

Posted on by rchapin

The TLDR; is to first use tr to replace all occurrences of any horizontal whitespace character with a single space, and then squeeze down any number of spaces to a single space and then define the delimiter for cut as a single space. The following example assumes that you want to see from the 5th column to the end of the line.

<do-something-to-generate-input| tr '[:blank:]' ' ' | tr -s ' ' | cut -d ' ' -f5-

The → Continue reading “Using cut with a delimiter of any amount of whitespace”

Running GUI apps locally as root in a non-root session

Posted on by rchapin

There are instances when you need to run an X Window application. For me this is often running a terminator instance as root so that I can create tabs and split the window as still be root in each of those terminals.

In order for the root user to be able to connect to the X server you need to provide it with “credentials”. In this case it is on the same box and not over the network so the → Continue reading “Running GUI apps locally as root in a non-root session”

VS Code “Test result not found for:” When Running Tests for a Python Project [SOLVED]

Posted on by rchapin

I finally was able to get Visual Studio Code set-up correctly to run and debug unit and integration tests for a Python 3.8 project that I am working on (I’ll add a link to that post here once it is up).

After making some changes to the code and adding a test I got the following error when trying to debug the test:

Test result not found for: ./mylibs/integration_tests/myclient_integration_test.py::MyClientIntegrationTest::test_happy_path

? An odd error message, to be sure.

After a little → Continue reading “VS Code “Test result not found for:” When Running Tests for a Python Project [SOLVED]”

Compiling Python Under Linux

Posted on by rchapin

The following should work with just about any version of Python. I am using it to compile, currently 3.10.x, on distros where those packages are not readily available for installation. The following is a quick how to on getting it compiled under both RedHat/CentOS/Almalinux and Debian based systems.

Download the Tarball for the Version You Want To Install

Download the tar.gz archive for the version that you want to install from here. Verify the download and then save the → Continue reading “Compiling Python Under Linux”

Using fc to Edit and Re-execute Bash Commands

Posted on by rchapin

I recently learned about the Bash built-in fc. It is a great tool that enables you to edit and re-execute commands from your bash history.

Oftentimes there is a command in your history that instead of just grepping through the history and then re-executing as-is you’ll want to make a modification or two. With fc you can first edit it in your favorite editor and then when closing the editor fc will execute the command.

For me, vim is my → Continue reading “Using fc to Edit and Re-execute Bash Commands”

© 2005 Ryan Chapin