Testing and reporting Invoke-command execution - powershell

Question

I have the following PowerShell script that creates a session with Windows server administrator account.I want to report in case of failure of Invoke-command the error and save it in a file
Below is the code that I wrote but if i tamper for example .json file(set a wrong username),execution fails and error_report.txt is not created
#Param(
$user = "lamda"
#)
$user_domain = (Get-WmiObject Win32_ComputerSystem).Domain
$user_computer = (Get-WmiObject Win32_ComputerSystem).Name
$file = "error_report.txt"
If ((Test-Path "creds.json") -eq $True)
{
$jsonfile = Get-ChildItem creds.json
if ($jsonfile.Length -eq 0)
{
#$file = "error_report.txt"
Set-Content -Path $file -Value "Error:The file 'creds.json' is empty"
break
}
else
{
$creds= (Get-Content creds.json | Out-String | ConvertFrom-Json)
$admin = $creds.username
$passwd = $creds.password
if (($admin) -and ($passwd))
{
$Password = ConvertTo-SecureString -String $passwd -AsPlainText -Force
$credential = [pscredential]::new($admin,$Password)
$command = Invoke-Command -ComputerName Server.$user_domain -FilePath
C:\SECnology\Data\Utilities\Updating.ps1 -ArgumentList
$user,$admin,$user_computer -Credential $credential
If ($command -eq $false)
{
$file = "error_report.txt"
Set-Content -Path $file -Value "Error:Session between user and server
could not be created,please check your Credentials"
}
break
}
elseif (([string]::IsNullOrEmpty($admin)) -or ([string
]::IsNullOrEmpty($passwd)))
{
#$file = "error_report.txt"
Set-Content -Path $file -Value "Error:One object of 'creds.json' seems
to be empty.Please check your file "
}
}
break
}
else
{
#$file = "error_report.txt"
Set-Content -Path $file -Value "Error:The file 'creds.json' does not exist"
}

Answer 1

I think the issue is the way you are defining the condition on your if statement.
You use -eq $false however if you connections fails it does not set the vale of command to $false it will leave command as a null as it return no value (it errorred).
What you can try is either use the null operator (!) in your if statement so:
If (!$command){Do stuff}
Or you can give you invoke command an error variable and check if that has a value when run.
$command = Invoke-Command -ComputerName Server.$user_domain -FilePath
C:\SECnology\Data\Utilities\Updating.ps1 -ArgumentList
$user,$admin,$user_computer -Credential $credential -ErrorVariable TheError
If ($TheError)
{Do stuff}