PowerShell Username Generator - Add to File/Check Against-CodePudding

I am creating usernames as such: first 3 letters of the first name then 4 randomly generated numbers. Ryan Smith = RYA4859. I am getting the random number from this PowerShell command:

Get-Random -Minimum 1000 -Maximum 10000

I need to know how to create a script that will add the username to a .txt file after it has been generated. I also want the script to first check the .txt file to see if the randomly generated number already already exists and if it does, generate a new 4 digit number that does not exist and then add that to the .txt file.

The flow should be:

generate random 4 digit number check txt file if number exists if yes - generate new number if no - append file and add generated number to file

CodePudding user response：

You want to run a do...until loop that runs until the randomly generated number doesn't exist in your text file

$file = "C:\users.txt"
$userId = "RYA"

# get the contents of your text file
$existingUserList = Get-Content $file

do
{
    $userNumber = Get-Random -Minimum 1000 -Maximum 10000

    # remove all alpha characters in the file, so only an array of numbers remains
    $userListReplaced = $existingUserList -replace "[^0-9]" , ''

# the loop runs until the randomly generated number is not in the array of numbers
} until (-not ($userNumber -in $userListReplaced))

# concatenates your user name with the random number
$user = $userId   $userNumber

# appends the concatenated username into the text file
$user | Out-File -FilePath $file -Append

CodePudding user response：

The main difference between the described version of the code in the comment on the question, and the following code, is that I'm appending the new user name to the file instead of over writing the file, and added a loop near the end to repeatedly ask if you want to continue.

function RandomDigits {
    [CmdletBinding()]
    param (
        [Parameter()]
        [int]$DigitCount = 2
    )
    $RandString = [string](Get-Random -Minimum 100000 -Maximum 10000000)
    $RandString.Substring($RandString.Length-$DigitCount)
}
function GenUserName {
    [CmdletBinding()]
    param(
        [Parameter(Mandatory = $true, Position = 0)]
        [string]$Prefix
    )
    "$Prefix$(RandomDigits 4)"
}
function ReadAndMatchRegex {
    [CmdletBinding()]
    param(
        [Parameter(Mandatory = $true, Position = 0)]
        [string]$Regex,
        [Parameter(Mandatory = $true, Position = 1)]
        [string]$Prompt,
        [Parameter(Mandatory = $false, Position = 2)]
        [string]$ErrMsg = "Incorrect, please enter needed info (Type 'exit' to exit)."
    )
    $FirstPass = $true
    do {
        if (-not $FirstPass) {
            Write-Host $ErrMsg -ForegroundColor Red
            Write-Host
        }
        $ReadText = Read-Host -Prompt $Prompt
        $ReadText = $ReadText.ToUpper()
        if($ReadText -eq 'exit') {exit}
        $FirstPass = $false
    } until ($ReadText -match $Regex)
    $ReadText
}
$Usernames = @{}
$UsernameFile = "$PSScriptRoot\Usernames.txt"
if(Test-Path -Path $UsernameFile -PathType Leaf) { 
    foreach($line in Get-Content $UsernameFile) { $Usernames[$Line]=$true }
}
do {
    Write-Host
    $UserPrefix = ReadAndMatchRegex '^[A-Z]{3}$' "Please enter 3 letters for user's ID"
    do {
        $NewUserName = GenUserName $UserPrefix
    } while ($Usernames.ContainsKey($NewUserName))
    $NewUserName | Out-File $UsernameFile -Append
    $UserNames[$NewUserName]=$true
    $UserNames.Keys
    $Continue = ReadAndMatchRegex '^(Y|y|YES|yes|Yes|N|n|NO|no|No)$' 'Coninue?[Y/N]'
} while ($Continue -match '^(Y|y|YES|yes|Yes)$')