Tag Archives: quick tip

21Mar/18

Quick Tip: PowerShell Supports Partial Parameter Names

Did you know that PowerShell supports the usage of partial parameter names? This isn’t such a big deal since tab completion is a thing… and if you’re writing code, you want to use the full parameter name to provide clarity and readability… but sometimes this is handy. Whether it’s for code golf, or just noodling around in the console, you don’t have to specify the full name of a parameter, just enough for it to be unique.

Here are some examples.

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07Feb/18

Quick Tip: Did the last command work or not?

In PowerShell, there is usually at least a few ways to do most tasks and detecting if the last command resulted in an error or if it worked is no exception. You could wrap code in a try/catch block, but sometimes that’s overkill. Regardless of your reason for wanting to get the work/borked status of the last command, here are a couple simple ways of doing it.

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07Dec/16

Quick Tip: Validate The Length Of An Integer

A little while ago, I fielded a question in the PowerShell Slack channel which was “How do I make sure a variable, which is an int, is of a certain length?”

Turns out it’s not too hard. You just need to use a little regex. Consider the following example.

$v6 is an int that is six digits long. $v2 is an int that is only two inches long. On lines three and four, we’re testing to see if each variables match the pattern ‘^\d{6}$’ which is regex speak for “start of the line, any digit, and six of them, end of the line”. The first one will be true, because it’s six digits, and the second one will be false. You could also use something like ‘^\d{4,6}$’ to validate that the int is between four and six digits long.

14Sep/16

Quick Tip: Allow A Null Value For An Object That Doesn’t Normally Allow It

In the PowerShell Slack channel (powershell.slack.com) a question came up along the lines of “I have a script that needs to pass a datetime object, but sometimes I’d like that datetime object to be null”. Never mind that maybe the script could be re-architected. Let’s solve this problem.

The issue is, if you try to assign a null value to a datetime object, you get an error.

The solution is super easy. Just make the thing nullable.

This will return no output. So when you’re declaring the variable that will hold your datetime object, just make sure you make it nullable.

Just for more proof this works as advertised, try this.

Cool!

09Mar/16

Quick Tip: Detecting Special Characters In A String The Easy Way

Here’s a super easy way to detect special characters in a string. Consider the following.

String1 has no special characters, String2 does. All I’m doing is comparing the string to “the string if we replace everything that isn’t a regular letter” using the -replace operator.

It’s just that easy.

You could do the same thing with the -match operator, too. The point here is looking at the regex.

30Sep/15

Quick Tip: Which Of These Groups Are These Users Members Of?

Here’s a quick PowerShell function I put together that you might like to use or pick pieces from. The point of the function is to take a list of usernames and a list of groups and tell you which users are members of which groups, including through nested group membership.

As you can see, this function requires the ActiveDirectory PowerShell module and the function is named Test-IsGroupMember. It takes two parameters called Usernames and Groups. Both are “object” types so they could be an array or a string. I didn’t want to make overloaded versions of a script this simple so I took this shortcut. It’s expected that the values in Usernames and Groups will be SamAccountNames.

On Line 15, I start the work. For all of the groups you pass the function, it determines the recursive group members and extracts the SamAccountName attribute of the members returned. Then to the output stream, we write that the currently evaluated group has a number of members. On Line 19, we check to see if any of the usernames in the Usernames parameter are contained within the members of the group. I could have used a Compare-Object here but I didn’t. If the user is present in both arrays, we report back.

Here are some examples of how I like using this function.

Pretty flexible.

16Sep/15

Quick Script Share: Tell Me Everyone With Access To This Directory

Trying something new. Here’s a quick script I threw together to satisfy a request along the lines of “tell me all the users who have access to this directory”. It’s easy to see all the groups that have access just by right-clicking a directory and going to the Security tab but it’s a pain to get all the users who belong to those groups – especially if there are nested groups (within nested groups, within nested groups). Hence, this script. In addition to the ActiveDirectory PowerShell module, you of course need to be able to read the ACL on the directory you are interested in so use your admin account.

In this experimental post, I’m not going to break down the script, but instead, I’ve quickly commented in-line most of the tricky bits. I think it’s pretty straight forward, but, I wrote it. Let me know what you think.