Category Archives: filesystem


Does A String Start Or End In A Certain Character?

Can you tell in PowerShell if a string ends in a specific character, or if it starts in one? Of course you can. Regex to the rescue!

It’s a pretty simple task, actually. Consider the following examples

In the first two examples, I’m checking to see if the string ends in a backslash. In the last two examples, I’m seeing if the string starts with one. The regex pattern being matched for the first two is .+?\$ . What’s that mean? Well, the first part .+? means “any character, and as many of them as it takes to get to the next part of the regex. The second part \\ means “a backslash” (because \ is the escape character, we’re basically escaping the escape character. The last part $ is the signal for the end of the line. Effectively what we have is “anything at all, where the last thing on the line is a backslash” which is exactly what we’re looking for. In the second two examples, I’ve just moved the \\ to the start of the line and started with ^ instead of ending with $ because ^ is the signal for the start of the line.

Now you can do things like this.

Here, I’m checking to see if the string ‘bears’ ends in a backslash, and if it doesn’t, I’m appending one.

Cool, right?


How To Send An Email Whenever A File Gets Changed

A little while ago, I fielded a question in the PowerShell Slack channel which was “How do I send an email automatically whenever a change is made to a specific file?”

Turns out it’s not too hard. You just need to set up a file watcher.

First, we create the watcher, which is just a FileSystemWatcher object. Technically the watcher watches the whole directory for changes (the path), which is why we add a filter.

Then we register an ObjectEvent, so that whenever the watcher sees a change event, it performs an action. In this case, I just have it writing output but it could easily be sending an email or performing some other task.

To get rid of the ObjectEvent, just run the following.

It’s just that easy!