Search text files for a given regular expression. This is for when findstr won't cut it due to its limited regexp support.

RegexFileSearch.ps1

param(
[Parameter(Position=0, Mandatory=$true)]
[string] $Pattern,
[Parameter(Position=1, Mandatory=$false)]
[string] $File,
[Parameter(Mandatory=$false)]
[string] $Directory,
[Parameter(Mandatory=$false)]
[string] $FileFilter,
[Parameter(Mandatory=$false)]
[switch] $Recurse = $false
)

if ($File.Length -gt 0)
{
    # If you specify one file, you can't specify Directory or FileFilter
    if ($Directory.Length -gt 0 -or $FileFilter.Length -gt 0 -or $Recurse -eq $true)
    {
        "Invalid syntax."
        return
    }
}
else
{
    # If you don't specify a file, you MUST specify Directory AND FileFilter
    if ($Directory.Length -lt 1 -or $FileFilter.Length -lt 1)
    {
        "Invalid syntax."
        return
    }
}

function SearchFile([string] $file, [bool] $displayFileName)
{
    $reader = New-Object System.IO.StreamReader($file)
    if ($reader -eq $null)
    {
        return
    }

    while ($null -ne ($buffer = $reader.ReadLine()))
    {
        if ($regex.IsMatch($buffer))
        {
            if ($displayFileName)
            {
                $file + ": " + $buffer
            }
            else
            {
                $buffer
            }
        }
    }

    $reader.Close()
}

$regex = New-Object System.Text.RegularExpressions.Regex($Pattern)
if ($File)
{
    SearchFile $File $false
}
else
{
    if ($Recurse)
    {
        $files = Get-ChildItem $Directory $FileFilter -Recurse
    }
    else
    {
        $files = Get-ChildItem $Directory $FileFilter
    }

    foreach ($oneFile in $files)
    {
        if (!($oneFile.PSIsContainer))
        {
            SearchFile $oneFile.FullName $true
        }
    }
}