Added Get-FileHash

Author: alan-null

strings/Get-FileHash.ps1

@@ -0,0 +1,55 @@
+function Get-FileHash {
+    <#
+.SYNOPSIS
+Returns hash from a file
+
+.DESCRIPTION
+Returns hash from a file using given hash algorithm.
+Default algorithm is:  'MD5'
+
+.PARAMETER FileName
+ Name/path of the file to be hashed
+
+.PARAMETER HashName
+Hash algorithm name
+
+.EXAMPLE
+Get-FileHash README.md
+Returns hash from "README.md" file, which is located in the current directory
+
+.EXAMPLE
+Get-FileHash "C:\README.md"
+Returns hash from "README.md" file, which is location is "C:\README.md"
+
+.EXAMPLE
+Get-FileHash README.md -HashName "sha256"
+Returns hash from "README.md" file, which is located in the current directory using 'sha256' algorithm
+
+#>
+
+    [CmdletBinding()]
+    param(
+        [Parameter(Mandatory = $true, Position = 0)]
+        [String]$FileName,
+        [Parameter(Mandatory = $false, Position = 1)]
+        [String]$HashName = "MD5"
+    )
+
+    process {
+        if (!(Test-Path $FileName)) {
+            $curLoc = Get-Location
+            $FileName = Join-Path $curLoc $FileName
+        }
+        if (!(Test-Path $FileName)) {
+            Write-Error "Could not find file $FileName"
+            exit
+        }
+        $FileName = Get-Item -Path $FileName
+        $FileStream = New-Object System.IO.FileStream($FileName, [System.IO.FileMode]::Open)
+        $StringBuilder = New-Object System.Text.StringBuilder
+        [System.Security.Cryptography.HashAlgorithm]::Create($HashName).ComputeHash($FileStream) | % { [Void]$StringBuilder.Append($_.ToString("x2")) }
+        $FileStream.Close()
+        $FileStream.Dispose()
+        $StringBuilder.ToString()
+    }
+}