Working with Files

PowerShell provides a rich set of cmdlets for reading, writing, and managing files. These cmdlets work with text, CSV, and JSON data out of the box.

Reading and Writing Text Files

Use Get-Content to read a file (returns an array of lines) and Set-Content to write content (overwrites the file):

$lines = Get-Content -Path ".\config.txt"
Set-Content -Path ".\output.txt" -Value "Hello, World!"

To append to an existing file instead of overwriting, use Add-Content:

Add-Content -Path ".\log.txt" -Value "New log entry"

Out-File is similar to Set-Content but preserves PowerShell's formatting. It is what the > redirect operator uses internally:

Get-Process | Out-File -Path ".\processes.txt"

Checking If a Path Exists

Always verify a path before reading or writing:

if (Test-Path ".\data.csv") {
    $data = Get-Content ".\data.csv"
}

Working with CSV Files

Import-Csv reads a CSV file and returns objects with properties matching the column headers. Export-Csv does the reverse:

$users = Import-Csv -Path ".\users.csv"
$users | Where-Object { $_.Department -eq "IT" } | Export-Csv -Path ".\it-users.csv" -NoTypeInformation

Working with JSON

Convert objects to JSON with ConvertTo-Json and parse JSON strings with ConvertFrom-Json:

$config = @{ Server = "prod-01"; Port = 443 }
$config | ConvertTo-Json | Set-Content ".\config.json"

$loaded = Get-Content ".\config.json" -Raw | ConvertFrom-Json
$loaded.Server   # prod-01

Building File Paths Safely

Use Join-Path and Split-Path instead of string concatenation to build cross-platform paths:

$fullPath = Join-Path -Path $HOME -ChildPath "Documents\report.csv"
$folder   = Split-Path -Path $fullPath -Parent     # parent directory
$fileName = Split-Path -Path $fullPath -Leaf        # file name only