Getting to Know the Join-Path Cmdlet in PowerShell

Welcome back to Wahmans PowerShell blog!

In today’s post, we’re diving into a very handy cmdlet: Join-Path. According to Microsoft, this cmdlet “Combines a path and a child path into a single path.” It might sound simple, but Join-Path is a powerful tool when working with file system paths in PowerShell. It helps avoid issues with path separators and makes your scripts more robust and readable.

The Basics of Join-Path

The syntax is simple:

Join-Path -Path <base-path> -ChildPath <child-path>

Let’s explore how to use this cmdlet in various scenarios, from beginner to more advanced use cases.

1. Beginner: Combine two static strings into a path

This is the most basic use of Join-Path. If you want to build a file system path without worrying about slashes, use this approach:

$base = "C:\Users\JohnDoe"
$child = "Documents"
$fullPath = Join-Path -Path $base -ChildPath $child
Write-Output $fullPath

Output:

C:\Users\JohnDoe\Documents

2. Intermediate: Use with Get-ChildItem

Need to find a specific file inside a known folder? Combine paths and then access them with Get-ChildItem:

$folder = "C:\Logs"
$filename = "system.log"
$filepath = Join-Path -Path $folder -ChildPath $filename

if (Test-Path $filepath) {
    Get-Content $filepath
} else {
    Write-Output "Log file not found: $filepath"
}

3. Advanced: Recursively build paths with multiple segments

If you need to build a deep path from several segments, you can chain Join-Path calls:

$segments = @("C:\Users", "JohnDoe", "Projects", "PowerShell")
$path = $segments[0]
for ($i = 1; $i -lt $segments.Count; $i++) {
    $path = Join-Path -Path $path -ChildPath $segments[$i]
}
Write-Output $path

Output:

C:\Users\JohnDoe\Projects\PowerShell

4. Advanced: Dynamic script to save log files by date

Let’s say you’re writing a script that saves logs into folders based on the current date. Here’s how Join-Path can help:

$baseDir = "C:\Logs"
$year = (Get-Date).Year
$month = (Get-Date).ToString("MM")
$day = (Get-Date).ToString("dd")

$logDir = Join-Path $baseDir $year
$logDir = Join-Path $logDir $month
$logDir = Join-Path $logDir $day

# Ensure directory exists
if (-not (Test-Path $logDir)) {
    New-Item -Path $logDir -ItemType Directory -Force | Out-Null
}

$logFile = Join-Path $logDir "script.log"
"Log entry at $(Get-Date)" | Out-File -FilePath $logFile -Append
Write-Output "Log written to: $logFile"

Final Thoughts

Join-Path is more than just a convenience—it’s a tool that helps avoid bugs and makes your code much more readable and portable. Whether you’re a beginner or an advanced scripter, there’s always a good reason to use this cmdlet when dealing with paths.

Happy scripting, and I will see you in the next post!

Wahmans Powershell Blog

Join-Path