Repeat foreach loop after all iteration completed in Powershell - powershell

Question

Anyone here can help me how to repeat the code from the beginning after all iteration in foreach loop has been completed. The code below will get all the files having 'qwerty' pattern inside the file, feed the list in foreach loop and display the filename and last 10 lines on each file and terminate the code if there is no new/updated file in certain amount of time
$today=(Get-date).Date
$FILES=Get-ChildItem -Path C:\Test\ | `
Where-Object {$_.LastWriteTime -ge $today} | `
Select-String -pattern "qwerty" | `
Select-Object FileName -Unique
foreach ($i in $FILES) {
Write-host $i -foregroundcolor red
Get-content -Path \\XXXXXX\$i -tail 10
Start-Sleep 1
}

Answer 1

You can use this:
For ($r = 0; $r -eq NumberOfTimesYouWantToRepeat; $r++) {
$today=(Get-date).Date
$FILES=Get-ChildItem -Path C:\Test\ | `
Where-Object {$_.LastWriteTime -ge $today} | `
Select-String -pattern "qwerty" | `
Select-Object FileName -Unique
foreach ($i in $FILES) {
Write-host $i -foregroundcolor red
Get-content -Path \\XXXXXX\$i -tail 10
Start-Sleep 1
}
}
PS: Replace TheNumberOfTimesToRepeat with the number of time you want to repeat.

Answer 2

If I understand the question properly, you would like to test for files in a certain folder containing a certain string. For each of these files, the last 10 lines should be displayed.
The first difficulty comes from the fact that you want to do this inside a loop and test new or updated files.
That means you need to keep track of files you have already tested and only display new or updated files. The code below uses a Hashtable $alreadyChecked for that so we can test if a file is either new or updated.
If no new or updated files are found during a certain time, the code should end. To do that, I'm using two other variables: $endTime and $checkTime.
$checkTime gets updated on every iteration, making it the current time
$endTime only gets updated if files were found.
$today = (Get-Date).Date
$sourceFolder = 'D:\Test'
$alreadyChecked = #{} # a Hashtable to keep track of files already checked
$maxMinutes = 5 # the max time in minutes to perform the loop when no new files or updates are added
$endTime = (Get-Date).AddMinutes($maxMinutes)
do {
$checkTime = Get-Date
$files = Get-ChildItem -Path $sourceFolder -File |
# only files created today and that have not been checked already
Where-Object {$_.LastWriteTime -ge $today -and
(!$alreadyChecked.ContainsKey($_.FullName) -or
$alreadyChecked[$_.FullName].LastWriteTime -ne $_.LastWriteTime) } |
ForEach-Object {
$filetime = $_.LastWriteTime
$_ | Select-String -Pattern "qwerty" -SimpleMatch | # -SimpleMatch if you don't use a Regex match
Select-Object Path, FileName, #{Name = 'LastWriteTime'; Expression = { $filetime }}
}
if ($files) {
foreach ($item in $files) {
Write-Host $item.Filename -ForegroundColor Red
Write-Host (Get-content -Path $item.Path -Tail 10)
Write-Host
# update the Hashtable to keep track of files already done
$alreadyChecked[$item.Path] = $item | Select-Object FileName, LastWriteTime
Start-Sleep 1
}
# files were found, so update the time to check for no updates/new files
$endTime = (Get-Date).AddMinutes($maxMinutes)
}
# exit the loop if no new or updated files have been found during $maxMinutes time
} while ($checkTime -le $endTime)
For demo, I'm using 5 minutes to wait for the loop to expire if no new or updated files are found, but you can change that to suit your needs.