Write-Output Failing Inside Foreach Loop - Powershell

Question

I am new to Powershell and I am wondering why this function doesn't work the way I want it too. The following function uncomments line in the hosts file of the computer specified. It works great! But I want the ability to output each line to the screen using a Write-Output and get the variable and store it in another array. This Write-Output doesn't do anything and I cannot add it to the array. Why? The above Write-Output works just fine.

function UnCommentHostsFile($ip){

   Write-Output "This Write-Output Works!"

   $hosts = $hosts | Foreach {

       #This part of the function works great!
       if ($_ -match $regex + $ip){
           $_.replace("#", "")

           #This is where I want to add it to an array and write-output but I can't.
       } 
       else {
           $_
       }

       #This does not output!
       Write-Output $_
   }
}

Any help would be greatly appreciated! Thanks! :)

mjolinor · Accepted Answer · 2014-03-26 00:07:04Z

1

To answer your question, when you do this:

$hosts = $hosts | Foreach {...}

everything that is output to the pipeline within that foreach script block is going to get re-directed to the variable $hosts.

Write-Output writes to the pipeline, and you're doing it within that script block.

If you want to explicitly write to the screen, use Write-Host, or Write-Verbose.

answered Mar 26, 2014 at 0:07

mjolinor

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6 Comments

Bob Over a year ago

This didn't work. I tried putting Write-Host, Write-Output, and Write-Verbose. Nothing is outputting to the screen but it is still correctly writing to the file.

Bob Over a year ago

Nothing. Nothing gets written to the screen in any of the three cases. If I place the Write- statement inside the if statement it does not get run. If I place Write-Host here my original Write-Output was it prints out every line in the file. I only want the lines that have been changed.

mjolinor Over a year ago

Are you sure any of it matched the If condition?

Bob Over a year ago

Yes, cause the file changes. Every time I run it, it comments out about 10 lines in the hosts.file. The next time I run it i switch it and it comments out a different set of IP's. This is very strange.

mjolinor Over a year ago

It is strange indeed. Running that with test data, I get it written to the console If I set $VerbosePreference to Continue I get Verbose console output along with it.

|

TheMadTechnician · Accepted Answer · 2014-03-26 15:26:54Z

0

You don't really need the Write-Output. Leave it as an object, and you can format that object however you want outside the function. I updated it so that for each line if it matches your regex it replaces # with nothing as you already had it, but I removed the Else clause because it was pointless. I changed $_.replace("#", "") to $_ = $_.replace("#", "") so that it actually updates the line in $Hosts instead of just echoing it. Then when all is said and done it outputs the entire $hosts updated lines and all.

function UnCommentHostsFile($ip){

   $hosts = $hosts | Foreach {

       #This part of the function works great!
       if ($_ -match $regex + $ip){
           $_ = $_.replace("#", "")

           #This is where I want to add it to an array and write-output but I can't.
       } 

       #This does not output!
   }
   $Hosts
}

Edit: When you call the function it should spit back whatever is in $Hosts, so it should output to the screen. No need to write-output or anything. It will show up on screen for the user, unless you are redirecting the output to something, in which case just add a bit to the pipe that prints it to the screen.

edited Mar 26, 2014 at 15:26

answered Mar 25, 2014 at 23:25

TheMadTechnician

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1 Comment

Bob Over a year ago

I need to write to the screen, some non technical people will be using this script, and save it to an array to run operations on specific entries. $_.replace("#", "") worked just fine and your code works too.

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