blog: add "Using direnv in PowerShell on Windows" post

src/content/blog/using-direnv-in-powershell-on-windows.md

@@ -0,0 +1,138 @@
+---
+title: "Using direnv in PowerShell on Windows"
+description: "Simple way to manage environment variables in PowerShell on Windows"
+date: 2026-02-17T12:50:32+07:00
+draft: false
+tags:
+  - script
+  - windows
+---
+
+# Background
+
+I want a `direnv` functionality in PowerShell running in Windows. Using the [official direnv](https://direnv.net/docs/installation.html) introduces problems because of platform compatibility (Unix-based vs Windows). So I decided to make a PowerShell script to load (and unload) `.envrc` file automatically just like `direnv` does.
+
+# How to Use
+
+- save the `direnv` script below to `$PROFILE\Scripts\direnv.ps1`.
+- add `. "$PSScriptRoot\Scripts\direnv.ps1"` line to `$PROFILE` to load it.
+
+# Script
+
+```powershell
+# PowerShell direnv alternative - Add to $PROFILE
+
+# Global variables to track state
+$global:EnvrcLoadedVars = @{}
+$global:LastEnvrcPath = $null
+
+function Load-Envrc {
+    param (
+        [string]$Path
+    )
+
+    $envrcFile = Join-Path $Path ".envrc"
+
+    if (Test-Path $envrcFile) {
+        # If we're loading the same .envrc, skip
+        if ($global:LastEnvrcPath -eq $envrcFile) {
+            return
+        }
+
+        # Unload previous environment variables
+        Unload-Envrc
+
+        Write-Host "direnv: loading $envrcFile" -ForegroundColor Green
+
+        # Read and parse .envrc file
+        Get-Content $envrcFile | ForEach-Object {
+            $line = $_.Trim()
+
+            # Skip empty lines and comments
+            if ($line -eq "" -or $line.StartsWith("#")) {
+                return
+            }
+
+            # Match export VAR=value or export VAR="value"
+            if ($line -match '^export\s+([A-Za-z_][A-Za-z0-9_]*)\s*=\s*(.+)$') {
+                $varName = $matches[1]
+                $varValue = $matches[2]
+
+                # Remove quotes if present
+                $varValue = $varValue -replace '^["'']|["'']$', ''
+
+                # Store the original value (if it exists) so we can restore it
+                if (Test-Path "env:$varName") {
+                    $global:EnvrcLoadedVars[$varName] = @{
+                        Original = (Get-Item "env:$varName").Value
+                        HasOriginal = $true
+                    }
+                } else {
+                    $global:EnvrcLoadedVars[$varName] = @{
+                        Original = $null
+                        HasOriginal = $false
+                    }
+                }
+
+                # Set the environment variable
+                Set-Item -Path "env:$varName" -Value $varValue
+                Write-Host "  export $varName" -ForegroundColor Gray
+            }
+        }
+
+        # Track the current .envrc path
+        $global:LastEnvrcPath = $envrcFile
+    }
+    else {
+        # No .envrc in current directory, unload if we had one loaded
+        if ($global:LastEnvrcPath -ne $null) {
+            Unload-Envrc
+        }
+    }
+}
+
+function Unload-Envrc {
+    if ($global:EnvrcLoadedVars.Count -gt 0) {
+        Write-Host "direnv: unloading" -ForegroundColor Yellow
+
+        foreach ($varName in $global:EnvrcLoadedVars.Keys) {
+            $varInfo = $global:EnvrcLoadedVars[$varName]
+
+            if ($varInfo.HasOriginal) {
+                # Restore original value
+                Set-Item -Path "env:$varName" -Value $varInfo.Original
+            } else {
+                # Remove the variable as it didn't exist before
+                Remove-Item -Path "env:$varName" -ErrorAction SilentlyContinue
+            }
+        }
+
+        $global:EnvrcLoadedVars = @{}
+        $global:LastEnvrcPath = $null
+    }
+}
+
+# Hook into directory change
+$global:LastDirectory = $PWD.Path
+
+function Invoke-EnvrcCheck {
+    if ($PWD.Path -ne $global:LastDirectory) {
+        $global:LastDirectory = $PWD.Path
+        Load-Envrc -Path $PWD.Path
+    }
+}
+
+# Override the prompt to check for .envrc on every command
+$global:OriginalPrompt = $function:prompt
+
+function prompt {
+    Invoke-EnvrcCheck
+    & $global:OriginalPrompt
+}
+
+# Load .envrc in the current directory when profile loads
+Load-Envrc -Path $PWD.Path
+
+Write-Host "direnv-like functionality loaded. .envrc files will be auto-loaded/unloaded on directory change." -ForegroundColor Cyan
+
+```