Create Linux users on PowerShell Core 6 with New-LocalLinuxUser

Harashita:

The function is New-LocalLinuxUser, not New-LocalUser :-), and you would need to be sure to dot source it..

General:
I'd suggest not making the description mandatory (I don't think Linux requires it? it has been a while), and I'd make the password expiration either be a string or a datetime object, and then you could output it in the correct format..  I reworked this.. (not tested.. but it should be ok..)

function New-LocalLinuxUser
{
    [cmdletbinding()]
    param 
    (
        [Parameter(Mandatory=$true, ValueFromPipelineByPropertyName = $true)]
        [ValidateLength(1,32)]
        [ValidateScript({
            if ($_ -cmatch '^[a-z_]([a-z0-9_-]{0,31}|[a-z0-9_-]{0,30}\$)$')
            {
                return $true
            }
            else 
            {
                throw 'The user account does not match default Linux rules'
            }
        })]
        [string]$Name,

        [Parameter(ValueFromPipelineByPropertyName = $true)]
        [string]$Description,

        [Parameter(Mandatory=$true, ValueFromPipelineByPropertyName = $true, ParameterSetName = 'byString')]
        [string]$AccountExpiresString,

        [parameter(Mandatory = $true, ValueFromPipelineByPropertyName = $true, ParameterSetName = 'byDateTime')]
        [datetime]$AccountExpiresObject,

        [Parameter(ValueFromPipelineByPropertyName = $true)]
        [pscredential]$Credential, 

        [parameter(ValueFromPipelineByPropertyName = $true)]
        [securestring]$Password
    )

    if ($null -eq $Credential -and $null -eq $Password)
    {
        throw 'Either a credential object, or a password string (secure) must be supplied'
    }

    if ($PSCmdlet.ParameterSetName -eq 'byString')
    {
        try 
        {
            $thisDate = [datetime]::Parse($AccountExpiresString)
            $ThisDateString = $thisDate.ToString('yyyy-MM-dd')
        }
        catch 
        {
            throw 'The AccountExpiresString is not a valid date'
        }
    }
    else 
    {
        $ThisDateString = $AccountExpiresObject.ToString('yyyy-MM-dd')
    }

    if ($Description)
    {
        /usr/sbin/useradd  $Name --comment $Description --expiredate $ThisDateString
    }
    else 
    {
        /usr/sbin/useradd  $Name --expiredate $ThisDateString
    }
     
    if ($LASTEXITCODE -ne 0)
    {
        Write-Error -Message ('Error creating {0}, ExitCode {1}' -f $Name, $LASTEXITCODE)
        Exit
    }
 
    echo $Password.GetNetworkCredential().Password | passwd --stdin $Name
 
    if ($LASTEXITCODE -ne 0)
    {
        Write-Error -Message ('Error setting password for {0}; ExitCode {1}' -f $Name, $LASTEXITCODE)
    }
}

The biggest changes I made:

1. ValidateScript to force the user name to match the Linux rules for user accounts as far as I understand them. (Thanks google 😉
   If someone has a case-insensitive
2. Added parametersetnames to allow a string for the user expiration date or a datetime object.
3. I changed the $Password parameter to a SecureString
4. I added a $Credential parameter to use a pscredential object
5. Modified all the parameters to accept pipeline input.. This could be modified further to accept multiple accounts for a bulk creation, or even a CSV input.
6. if both the $Password & $Credential parameters are null, it throws an error.  (I don't know of way to make both of them mandatory without creating a ridiculous number of parameter sets to cover every situation)
7. If the expiration date is sent in as a string, it does a datetime parse test against it to validate it really is a date, and then creates a string out of it with the right format.
8. If the expiratiopn date is sent as datetime object, I create the same string in the right format.
9. Modified the output errors to include the $LastExitCode
10. Made the comment ($Description) optional

David F.