How to pass multiple computer names to cmdlet using pipeline?

PowerShell Help
1

Hello,

I have a list of computer names (it includes two or more items), How I can pass the list to a cmdlet (e.g., get-hotfix) using pipeline parameter binding?

My computers.csv file:

ComputerName
server2012
desktop1

I have tried this command:

import-csv computers.csv | get-hotfix

But its output contains list of hot fixes only for one of computers:

Source        Description      HotFixID      InstalledBy          InstalledOn
------        -----------      --------      -----------          -----------
DESKTOP1      Update           KB2693643     NT AUTHORITY\SYSTEM  1/4/2017 12:00:00 AM
DESKTOP1      Update           KB3199986     NT AUTHORITY\SYSTEM  1/5/2017 12:00:00 AM
DESKTOP1      Security Update  KB3209498     NT AUTHORITY\SYSTEM  1/5/2017 12:00:00 AM
DESKTOP1      Security Update  KB3206632     NT AUTHORITY\SYSTEM  1/5/2017 12:00:00 AM

I can get list of hot fixes for all of computers using parentheses:

PS C:\Users\johndoe\documents> get-hotfix -computername (import-csv computers.csv | select -expand computername)
 
Source        Description      HotFixID      InstalledBy          InstalledOn
------        -----------      --------      -----------          -----------
SERVER2012    Update           KB2919355     MACLOCALDOMAIN\Ad... 3/21/2014 12:00:00 AM
SERVER2012    Update           KB2919442     MACLOCALDOMAIN\Ad... 3/21/2014 12:00:00 AM
SERVER2012    Update           KB2937220     MACLOCALDOMAIN\Ad... 3/21/2014 12:00:00 AM
SERVER2012    Update           KB2938772     MACLOCALDOMAIN\Ad... 3/21/2014 12:00:00 AM
SERVER2012    Update           KB2939471     MACLOCALDOMAIN\Ad... 3/21/2014 12:00:00 AM
SERVER2012    Hotfix           KB2949621     MACLOCALDOMAIN\Ad... 3/21/2014 12:00:00 AM
DESKTOP1      Update           KB2693643     NT AUTHORITY\SYSTEM  1/4/2017 12:00:00 AM
DESKTOP1      Update           KB3199986     NT AUTHORITY\SYSTEM  1/5/2017 12:00:00 AM
DESKTOP1      Security Update  KB3209498     NT AUTHORITY\SYSTEM  1/5/2017 12:00:00 AM
DESKTOP1      Security Update  KB3206632     NT AUTHORITY\SYSTEM  1/5/2017 12:00:00 AM

But I expected same output for both commands.

My environment: Windows 10 Enterprise 64-bit, powershell 5.1.14393.576

2

It would be easier to help if we could see your code. But from your explanation, it sounds as if you did not use a process block.

Do a search for begin, end and process blocks, that should point you in the right direction.

3

Hello, Christian, thank you for your answer! I have not code at all because I enter commands using powershell command line, and I have a single command that produces an unexpected (for me) output:

PS C:\Users\johndoe\documents> import-csv computers.csv | get-hotfix

Source        Description      HotFixID      InstalledBy          InstalledOn
------        -----------      --------      -----------          -----------
DESKTOP1      Update           KB2693643     NT AUTHORITY\SYSTEM  1/4/2017 12:00:00 AM
DESKTOP1      Update           KB3199986     NT AUTHORITY\SYSTEM  1/5/2017 12:00:00 AM
DESKTOP1      Security Update  KB3209498     NT AUTHORITY\SYSTEM  1/5/2017 12:00:00 AM
DESKTOP1      Security Update  KB3206632     NT AUTHORITY\SYSTEM  1/5/2017 12:00:00 AM

I expect that it should print list of hot fixes for each computer from the computers.csv file (posted above), because:

  1. import-csv produces a list of PSCustomObject-s
  2. each PSCustomObject has property ‘ComputerName’ with a String value
  3. get-hotfix cmdlet supports pipeline input with ByPropertyName binding
  4. when I use import-csv combined (pipelined) with an another command (e.g. new-aduser) it works as I expect and creates all users from csv list instead of creating a single user

I have an ugly solution for now:

PS C:\Users\johndoe\documents> import-csv computers.csv | foreach { get-hotfix -computername $_.computername }

Source        Description      HotFixID      InstalledBy          InstalledOn
------        -----------      --------      -----------          -----------
SERVER2012    Update           KB2919355     MACLOCALDOMAIN\Ad... 3/21/2014 12:00:00 AM
SERVER2012    Update           KB2919442     MACLOCALDOMAIN\Ad... 3/21/2014 12:00:00 AM
SERVER2012    Update           KB2937220     MACLOCALDOMAIN\Ad... 3/21/2014 12:00:00 AM
SERVER2012    Update           KB2938772     MACLOCALDOMAIN\Ad... 3/21/2014 12:00:00 AM
SERVER2012    Update           KB2939471     MACLOCALDOMAIN\Ad... 3/21/2014 12:00:00 AM
SERVER2012    Hotfix           KB2949621     MACLOCALDOMAIN\Ad... 3/21/2014 12:00:00 AM
DESKTOP1      Update           KB2693643     NT AUTHORITY\SYSTEM  1/4/2017 12:00:00 AM
DESKTOP1      Update           KB3199986     NT AUTHORITY\SYSTEM  1/5/2017 12:00:00 AM
DESKTOP1      Security Update  KB3209498     NT AUTHORITY\SYSTEM  1/5/2017 12:00:00 AM
DESKTOP1      Security Update  KB3206632     NT AUTHORITY\SYSTEM  1/5/2017 12:00:00 AM

But I think that this task may be solved without foreach cmdlet.

4

computername parameter accepts an array.

[-ComputerName ]

get-hotfix -ComputerName (get-content .\servers.txt)

or

$arrayofcomputersex = (get-content .\servers.txt)
get-hotfix -ComputerName $arrayofcomputersex