A crash course on PowerShell for Developers

While some developers might consider web development on Windows to be lacking compared to Linux and macOS, PowerShell has greatly improved the web development workflow on Windows and is not just for Admins. PowerShell gives you access to the computers file system, allows you to make server requests as well as interact witha huge amount of other technologies. PowerShell is a scripting language and command-line shell so it has a lot of potential!

If you’re a developer in the Microsoft ecosystem then learning PowerShell will help improve your workflow. This crash courseis designed for Windows users, however PowerShell is cross-platform and can be used on Linux and macOS.

This course uses PowerShell version 7.03 and assumes you have a basic understanding of what a command-line shell is and that you’ve perhaps opened and explored one before or are familiar with Linux or macOS shells.If not, no worries, you can still follow along and learn a few things. This course rapidly goes through a lot of information,as it’s intended to get you working with PowerShell quickly. However, I will be diving deep into the concepts and commands introduced here in upcoming articles.

Command-let

PowerShell uses something called a cmdlet (command-let) which is described by Microsoft as a “lightweight command that is used in the PowerShell environment”. These are very similar to a function in other programming languages.

For example in JavaScript you might invoke or call a function like this:

exampleFunction(Value1);

However, the cmdlet syntax is a bit different. For example we could write something like this.

New-Item -Name "Value1"

We’ll dive deeper into into the cmdlet syntax later, but for now let’s look at some basics you should know about cmdlets:

• PowerShell calls its arguments Parameters
• Parameters always start with a dash, -Path, -Name, -PassThru.
• Parameters are order-independent, we don’t need to just provide parameter values in a specific order we need to provide the parameter names.
• Some parameters don’t have values, they will only have one effect. These are called switch parameters

# -PassThru is a switch parameter
Set-Location -Path "C:\Users\jordan\Desktop\" -PassThru

• PowerShell is not case sensitive: New-Item, new-item & neW-ITem would all work the same.
• Cmdlets always use the naming pattern of verb-noun to help us figure out what they do.
• PowerShell can sometimes assume that a value type is a string without wrapping the value in double quotes.

# these are the same
New-Item -Name "Value1"
New-Item -Name Value1

• Some parameters are Positional. Ifa parameter is positional then we do not need to include the parameter name, however the order of a positional parameter is important. More on that later.

# these are the same, the second cmdlet uses the positional parameter -Path 
New-Item -Path "c:\" -Name "Value1" -ItemType "directory"
New-Item "c:\" -Name "Value1" -ItemType "directory"

• Many cmdlets have aliases which are meant to make them easier to use. You can also create yourown aliases but we’ll cover that another time.

# these cmdlets are the same, ni is an alias
new-item
ni

# these cmdlets are the same
Get-History
ghy
h
history

• Parameters can also have aliases

I wanted to start with the basics of cmdlets because you’ll often run across many different variations of a PowerShell cmdlet,and it can be confusing at first. While there are many variations and shortcuts to write a PowerShell script, I recommend that you try andbegin with the long-hand versions for readability.

Get-Help

One of the first things you should know when working with PowerShell is where to look for information about commands. Luckilyyou can use the Get-Help cmdlet to accomplish this.

There are 3 different types of help information that can be display:

1. Help files. These are files that can be downloaded and installed locally on your computers. You can use the cmdlet Update-Help to install these files.
2. Auto-generated help info. These are much smaller bits of help information that PowerShell generates if no help files are available on your computer locally.
3. Online help. Get-Help can open online help information from the Microsoft TechNet Library

Here’s how we can use it to display help about the new-item command.

# this will display the help files for the new-item cmdlet one page at a time.
Get-Help new-item

We can also use the PowerShell function help that runs the Get-Help cmdlet to do the same thing.

# these do the same thing. man is an alias of help
help new-item
man new-item

You might recognize man which is kind of like the Unix verion of Get-Help. Many aliases are from other systems to make it easier to transition which is nice 👍.

In addition to the general information you can also pass in the -examples parameter which will display examples of how cmdlets and functions are used.

# this will display examples of how to use new-item
help new-item -examples

If at anytime you need to exit the help pages you can simply press q or ctrl + c.

Opening the online help results:

# this will open the online help results for new-item
help new-item -online

Navigating

Learning how to effectively navigate a file system will speed up your workflow and make for a better overall experience. If you execute a command while in the wrong directory it can be confusing or worst case, completely ruin your day.

Understanding where you are is really the first step in all navigation.

You can determine where you are in the file system by using the Get-Location cmdlet. This is the similar to the pwd command on Unix systems. You can still use pwd which is an alias for Get-Location.

# this will display your current location
Get-Location

# my current location 
Path
----
C:\Users\jordan

# these are the same 
Get-Location
gl
pwd

Change Locations

Once you know where you currently are you can change your location with the Set-Location cmdlet. You can also use thealias cd (change directory) that comes from Unix. You’ll often see cd in documentation and if you’re used to Unix then it might be easier to remember. ¹

The Set-Location cmdlet has a -Path parameter which will take in the target path.

# these all do the same thing
Set-Location -Path "C:\Users\jordan\Desktop\"
sl -Path "C:\Users\jordan\Desktop\"
cd -Path "C:\Users\jordan\Desktop\"

Because the -Path parameter is has a positional value of 0 you can omit it and just indicate the target location

# this are the same
cd "C:\Users\jordan\Desktop\"
cd -Path "C:\Users\jordan\Desktop\"

You can also use the -PassThru parameter, which will return the location. This can be a handy way to confirm you’re in the correct location after navigating to a new directory without using a separate cmdlet like pwd.

cd "C:\Users\jordan\Desktop\" -PassThru

Path
----
C:\Users\jorda\Desktop

You can take advantage of Tab Completion when entering a path so you don’t have to the whole thing out.

You can also use a few shortcuts to change locations.

# this will take you to the logged in users directory
cd ~

To move up one level in the file system you could write the following:

# moves up one level
cd ..

You might be familiar with using the two dot characters (without a space) .. if you have imported JavaScript modules or linked CSS files from differentdirectories.

If you’re using PowerShell v6.2 or higher than you can also use - and + as values for the -Path parameter. PowerShell keeps a short history of the last 20 locations and you can use those characters to navigate between them.

# this will navigate backwards in your history 
cd -
# this will navigate forwards in your history 
cd +

Listing the contents of a directory

Once you’ve successfully navigated to your desired location it can be helpful to find out exactly what files or directories are inside.

You can use the Get-ChildItem cmdlet to list all the items in one or more locations. You can also use the alias ls from Unix.

# this will return the names of all the files in the current directory 
Get-ChildItem -Name

# these do the same thing
ls -Name
gci -Name

By default, if no parameters are entered Get-ChildItem will list:

• Mode
• LastWriteTime
• File Size (Length)
• Name

# heres what the default looks like in my case
Get-ChildItem 

    Directory: C:\Users\jordan\Desktop

Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 2020-08-20 1:21 PM testing
-a--- 2020-08-21 5:22 PM 1593744 audio-image.jpg

View the contents of a file

Now that you’ve navigated to your desired location and you’ve listed out all the contents of a directory, perhaps you’d like to see the contents of a specific file.

You can use the Get-Content cmdlet to display the contents of a file. The aliases for this cmdlet are cat which comes from Unix and type.

# this will display the contents of the animals.json file in my current directory 
Get-Content -Path animals.json

# the contents of animals.json
{
  "name": "lion",
  "color": "gold",
  "description": "king of the jungle",
  "friend": "hippo",
  "food": "zebra"
}

Because -Path is a positional parameter with a position of 0 we can omit it and just write

# this will have the same result as above
Get-Content animals.json

Because many files contain a ton of information you might want to limit the amount that is displayed. You can do that by using the-TotalCount parameter and specify the total number of lines you want displayed.

Get-Content animals.json -TotalCount 3

{
  "name": "lion",
  "color": "gold",

Create new files and directories

If you’re a web developer you’re likely creating new files all the time as your projects grow. Luckily PowerShell makes it pretty easyto create new files and directories using the New-Item cmdlet.

This course is just going to cover the basics of New-Item but I will be deep diving into that cmdlet in future posts because it’s such a powerful command that you can leverage to make your web development workflow more efficient.

Creating new files

You can create a new file using the New-Item cmdlet, which has an alias ni.

# here's a basic example of creating a new file
New-Item -Path . -Name "index.html" -ItemType "file"

In the example above we created a file in the current directory called index.html. We used a parameter called -ItemType to specify the file type.

You can write a shorthand version that takes advantage of an alias, positional parameters and default values. -Path has a position of 0 and it’s default value is the current location. You can also pass in the name of the file into the -Path parameter. We can also omit the -ItemType parameter in this case because we are including the file extension in the name.

So, the shorthand could look something like this:

# these are the same
ni index.html
New-Item -Path . -Name "index.html" -ItemType "file"

You can also easily create multiple files with the same command. -Path takes in multiple strings, seperated by a comma. Here we create two files, app.js and index.html.

# this will create two files in the current directory
New-Item app.js, index.html -Type "file"

You can also create multiple files at different locations by specifying the paths. In this example we create two different files, app.js created at c:\Users\Jordan\Client-Projects\ and index.js createdat c:\Users\Jordan\Personal-Projects\.

# here we are creating two files, at two different locations
New-Item "c:\Users\Jordan\Client-Projects\app.js", "c:\Users\Jordan\Personal-Projects\index.js"

Creating new directories

To create a new directory you can also use the New-Item cmdlet, and specify “directory” as the Item-Type

# these are the same
New-Item -Path . -Name "styles" -ItemType "directory" 
New-Item "styles" -ItemType "directory" 
ni "styles" -ItemType "directory"
ni "styles" -Type "directory"

If you’re coming from a Unix background you might be familiar with the mkdir (make directory) command. In PowerShell mkdir is a function that references the New-Item cmdlet and hard codes the -Type parameter as Directory.

It’s a convenient function that makes is a bit shorter and easier to remember, particularly if you’re coming from other shells.Here’s how you can use it:

# creates a directory in the current location called client
mkdir client 

# creates a directory in the root of the C: drive called foo
mkdir C:\foo

And of course its easy to create multiple directories as well. Here we create directories named styles, client-scripts and imagesin the current location.

# these do the same thing
mkdir styles, client-scripts, images
New-Item styles, client-scripts, images -ItemType "directory" 

Combining cmdlets

Now that you know a couple of the basic cmdlets, you can begin to combine them and start to unleash some of the real potential of working with PowerShell.

There are a few ways to combine cmdlets together, all producing different results. Let’s have a look at some of the ways we can combine commands.

Statement Operator

This is one of the easiest ways to combine cmdlets. Using a semicolon (;) you can write multiple commands on one line.

# create a directory and then navigate to it
mkdir styles; cd styles 

In the example above we created a new directory called styles then we navigated to it using cd. However the statement operator has it’s limitations when used to combine commands since the second command will execute regardless of if the first one was successful.

Luckily, there are a couple of other operators we can use to avoid errors and add some logic when creating more complex commands.

Pipeline Chain Operators

I’m not going to get too deep into pipes right now but I do want to keep you excited about the possibilities when working with PowerShell.So I will introduce pipeline chain operatorsand provide some examples to show you how you can use them.

For now you just need to know the basics of pipeline chain operators:

• && This operator will run the second command (on the right hand side of the pipe) only if the first command succeeds.
• || This operator will run the second command (on the right hand side of the pipe) only if the first one fails.

Here are a couple basic examples using the Write-Output cmdlet which can display or print to the PowerShell console, and the Write-Error cmdletwhich we will use to create an error to simulate a failed command. This way you can better visualize the results of the commands.

Here we use the && operator with two successful commands. Since the first command (the one on the left hand side of the pipe) is successful the second command runs.

Write-Output 'First command is successful' && Write-Output 'so this second command is runs'

# console output
First command is successful
so this second command is runs

Here we the first command fails and so the second command will not execute:

Write-Error "This command failed" && Write-Output "This command will not run"

# console output
Write-Error "This command failed"

Using the || operator

Write-Output "The first command was successful" || Write-Output "so this command will not run"

# console output
"The first command was successful"

Using the || operator with the first command failing:

Write-Error "This command failed" || Write-Output "so the second command runs"

# console output
Write-Error: This command failed
so the second command runs

So that’s all good and fine you might say, but how about a practical example?

Here’s an example taking advantage of the pipeline chain operators, to quicly create a project directory structure:

# create a basic web development structure
mkdir todo-app && cd todo-app `
&& mkdir styles, scripts, images `
&& ni C:\Users\jordan\Projects\todo-app\styles\styles.css, index.html, README.md

# console output
    Directory: C:\Users\jordan\Projects\todo-app

Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 2020-08-21 1:10 PM todo-app

    Directory: C:\Users\jordan\Desktop\todo-app

Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 2020-08-21 1:10 PM styles
d---- 2020-08-21 1:10 PM scripts
d---- 2020-08-21 1:10 PM images

    Directory: C:\Users\jordan\Projects\todo-app\styles

Mode LastWriteTime Length Name
---- ------------- ------ ----
-a--- 2020-08-21 1:10 PM 0 styles.css

    Directory: C:\Users\jordan\Projects\todo-app

Mode LastWriteTime Length Name
---- ------------- ------ ----
-a--- 2020-08-21 1:10 PM 0 index.html
-a--- 2020-08-21 1:10 PM 0 README.md

In the example above we create a project directory called todo-app, if that command is successful then we navigate inside the todo-appdirectory and create 3 directories called images, scripts and styles. Then we use the ni cmdlet to create 3 files, index.html and README.mdwhich will be at the root of the todo-app directory and a styles.css file that will be located in the styles directory. You can use a back tick ( ` ) to create a newline in the command for readability.

Because we used the && operator each command will only run if the one before it is successful. You can see with this example how we can combine commands to quicly create a project structure. This concept starts to become really helpful when we combine commands like this in custom scripts that you can easily reuse.

Wrap up

In this crash course you learned how you can use PowerShell to increase your web development workflow by using basci cmdlets. Youlearned the basic syntax of a cmdlet, how to find information in PowerShell, how to navigate, create files and directories as well as combine commands to create project structures.

Don’t worry if you don’t understand everything that was covered in this crash course. Re-read it as many times as you need to and have a look at some of the resources I linked to. Using a shell to perform regular tasks takes time to become comfortable with but the more you use it the better you’ll become and soon you’ll become a power user!

In future posts I will dive deeper into cmdlets and show you some more web development focused commands such as how to make server requests and write custom scripts that you can reuse in your projects.

Update-Help

1. While using aliases that come from Unix might be more familiar, consider that if you’re writing PowerShell scripts that will be used by others it might be thoughtful to use the PowerShell cmdlet names and not aliases for better readability. ↩