passing on variables

I am new to Powershell, and I need help on the following:

I put a script where a varibale is processed and then passed on to a command within the same script, the issue is that this command fails because it does not take the variabe , but i know for sure that the varibale has the right value, can somebody please explain to me what is wrong\missing, example below

$pathd = $path.Replace($user," “)
#$pathd= “/vol/vol1/qt2/”
echo " $pathd”
$ql= select-string u:\powershell\qline.txt -pattern “$pathd” | ForEach-Object {$_.Line}
echo “this is quota line $ql”
$q= $ql.Replace($pathd," ")
echo “this is quota $q”

to run the above " script /vol/vol1/qt1/username username "

the output is

this is quota line
You cannot call a method on a null-valued expression.
At U:\powershell\aa.ps1:8 char:1

  • $q= $ql.Replace($pathd," ")
  •   + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
      + FullyQualifiedErrorId : InvokeMethodOnNull

so $q fails because $ql is empty, and I can not figure out why, $pathd is correctly processed and its value is " /vol/vol1/qt1/"
$ql works fine if I pass the variable direclty as “/vol/vol1/qt1/” and it gets the value of “600”

qline.txt contains the lines below

Dave Wyatt: Edit: Moved to PowerShell Q&A Forum.

This line:

$pathd = $path.Replace($user," ")

replaces the value of $user with a single space character inside $path. In your commented out line of

#$pathd= "/vol/vol1/qt2/"

There is no space character. That is important; the whitespace becomes part of the pattern.

thanks very much, i replaced that line with “$pathd = $path -replace $user” and my script works fine, many thanks again