Error in Powershell with foreach loop

hi,

i use piece of code check if 1 or more services running on list of servers. if present , not running start service. list of servers in textfile. works well, seems check 1 time many, generates error :

get-wmiobject : cannot validate argument on parameter 'computername'. argument null or empty. supply argument th
@ not null or empty , try command again.
@ d:\scripts\ps\servicetest2.ps1:17 char:63
+     $objwmiservice = get-wmiobject -class win32_service -computer <<<<  $computer
    + categoryinfo          : invaliddata: (:) [get-wmiobject], parameterbindingvalidationexception
    + fullyqualifiederrorid : parameterargumentvalidationerror,microsoft.powershell.commands.getwmiobjectcommand

the code is:

 

# setup trap catch exceptions
trap [exception]
{
    write-error $("trapped: " + $_.exception.message);
}
# read computers text file

$computers = (get-content d:\scripts\computers.txt);
$start = $true;
# setup service array service names want check running
$servicearray = 'spooler';
# powershell knows it's array working simple
foreach($computer in $computers)
{
    write-host "checking $computer";
    $objwmiservice = get-wmiobject -class win32_service -computer $computer
    foreach($service in $objwmiservice)
    {
        # check each service specicfied in $servicearray
        foreach($srv in $servicearray)
        {
            if($service.name -eq $srv)
            {
                write-host "$srv present on $computer.";
                if($service.state -eq "running")
                {
                    write-host "$srv running on $computer";
                }
                else
                {
                    write-host "$srv not running on $computer";
                    # if $start true script attempt start service if stopped
                    if($start -eq $true)
                    {
                        # attempt start current service on current computer
                        $serviceinstance = (get-wmiobject -computer $computer win32_service -filter "name='$srv'");
                        $name = $serviceinstance.name;
                        write-host "attempting start $name  on $computer."
                        $serviceinstance.startservice() | out-null;
                        # refresh object instance new data
                        $serviceinstance = (get-wmiobject -computer $computer win32_service -filter "name='$srv'");
                        $state = $serviceinstance.state;
                        write-host "$name ""$state"" on  $computer.";
                        end if
                    }
                }
            }
        }
    }
}

 

 

what can rid of error?

i hope 1 can me out

thanks,

jansietje

 

this structure:

if ($computer) {code}

 

ensures code not run on lines only a character return. if possible lines have 1 or more spaces, need use trim() function.

$computer = $computer.trim()  if ($computer){code}

 

---

richard mueller - mvp directory services

Windows Server  >  Windows PowerShell