Various technologies have silly names for things, although in some rare cases the names are directly correlated to an activity. While delivering a number of PowerShell and RESTful API sessions at VMware User Groups, I used the term dot sourcing to describe a quick testing activity for scripts. Afterwards, I received questions on what this meant – meaning I took the knowledge for granted. This “curse of knowledge” can really bite me in the pants at times, so I figured it’d be worth writing down what dot sourcing is and how it works in a blog post. Plus, it’s easier to reference in the future. 🙂
In my case, I’m talking about the use of a specific syntax within PowerShell to “informally” load a script. I often use it to load a specific script contained within a module, such as the one I’m contributing to for Rubrik, without having to reload the entire module. The syntax is:
. ./path/to/script.ps1
This activity will cause the script to become available in the scope of my PowerShell console, which is handy for a number of reasons:
- Pass arguments to a script using Intellisense / Autocomplete to tab through the options (I’m lazy).
- Include the script within another script or function to validate any changes made to the code (trying new things).
- More realistic testing of the script without worrying about permanent placement of the file (related to trying new things).
To demonstrate this, I’ll pull up a list of PowerShell scripts from my local copy of the Rubrik module. I’ve made a change to the Connect-Rubrik.ps1 file and now want to test it locally. If I unload the module and then try to run the script, the console’s scope has no idea what I’m referring to, which has been demonstrated below:
However, using the dot sourcing technique, I can temporarily load the script for testing.
. .\Connect-Rubrik.ps1
This is a handy little trick for tinkering around with PowerShell scripts on your local machine without having to rely upon more formal installation or deployment methods. Sometimes I think it’s so simple that it doesn’t get enough attention or detailed instructions. I hope this helps with your coding – enjoy!
