Update AssemblyInfo.cs files through one line commandline

I had written powershell script. But the requirement was one liner which i think is too complex to achieve. Here's my script
/*Powershell Script*/

function Update-SourceVersion
{
Param ([string]$Version)
$NewVersion = 'AssemblyVersion("' + $Version + '")';
$NewFileVersion = 'AssemblyFileVersion("' + $Version + '")';

foreach ($o in $input)
{
Write-output $o.FullName
$TmpFile = $o.FullName + ".tmp"

get-content $o.FullName |
%{$_ -replace 'AssemblyVersion\("[0-9]+(\.([0-9]+|\*)){1,3}"\)', $NewVersion } |
%{$_ -replace 'AssemblyFileVersion\("[0-9]+(\.([0-9]+|\*)){1,3}"\)', $NewFileVersion } > $TmpFile

move-item $TmpFile $o.FullName -force


}
}

function Update-AllAssemblyInfoFiles ( $version )
{
foreach ($file in "AssemblyInfo.cs", "AssemblyInfo.vb" )
{
get-childitem -recurse |? {$_.Name -eq $file} | Update-SourceVersion $version ;
}
}
$version1=Get-Content C:\Users\Ashutosh\Desktop\testapp\testapp\buildVersion.txt
Set-Location C:\Users\Ashutosh\Desktop\testapp\testapp;
Update-AllAssemblyInfoFiles $version1;