using a delimiter to split files names in powershell - powershell

Question

I use a simple function to download files and return the path to me when updating computers for simplicity.
I was stuck on why it was not working then realized that the proxy is appending a random number to the filename so instead of it being 12345.zip it is actually 8493830_12345.zip.
I have tried to find the file using the "_" as a split but while there are no errors, the file is not being returned and I have checked it is there manually.
function FileCheck {
$fileName.Split("_")[1]
$fileName = "{0}.zip" -f 12345
Download -ZipFileName $($fileName) -OutputDirectory $env:temp
$SleepTime = 300
$sleepElapsed = 0
$sleepInterval = 20
Start-Sleep $sleepInterval
$file = Get-ChildItem -Path $env:temp -Filter "$fileName*"
if ($file -ne $null) {
return $file[0].FullName
}
Start-Sleep($sleepInterval)
$sleepElapsed += $sleepInterval
if (($SleepTime) -le $sleepElapsed){
# Check for file with given prefix
$file = Get-ChildItem -Path $env:temp -Filter "$fileName*"
if ($file -eq $null) {
Write-Error 'file not found'
return $null
}
return $file[0].FullName
}
}
I am guessing the split is not working but googling and moving the filename.split has not worked for me. Any help is appreciated

Answer 1

Well, your split is doing nothing at all. You haven't defined $filename, but if you had, and it had an underscore, then $filename.split('_') would return two or more strings, depending on how many underscores were in the original string, but you never capture the result. I think the real problem here is the filter you are applying to Get-ChildItem later in your function.
$file = Get-ChildItem -Path $env:temp -Filter "$fileName*"
That will look for files beginning with $fileName, which you define on line 4 to be "12345.zip". That is exactly the opposite of what you want to be looking for. You need to move the asterisk to before $fileName, so it looks like this:
$file = Get-ChildItem -Path $env:temp -Filter "*$fileName"
That will return all files that end with "12345.zip", which would include things like:
myfuzzyhippo12345.zip
learn-to-count-12345.zip
8493830_12345.zip
Basically anything that ends in 12345.zip. Also, it appears that you are under the impression that executing a return $file[0].fullname or return $null will stop the function. That's a mistake. A function runs to completion unless exited early by something like a break command. Also, everything not explicitly captured or redirected will be passed back from the function, so reading through your function people are likely to get the output of your $filename.split('_') line, then possibly $null or $filename[0].fullname.
Lastly, it appears that you're trying to look for the file, if you don't find it to wait a bit, and try again, until $sleepElapsed is greater than $sleepTime. What you want here is a While or a Do/While loop. Here's what I'd do...
function FileCheck {
Param(
$fileName = '12345.zip',
$SleepTime = 300,
$sleepElapsed = 0,
$sleepInterval = 20
)
Download -ZipFileName $($fileName) -OutputDirectory $env:temp
Do{
Start-Sleep $sleepInterval
$sleepElapsed = $sleepElapsed + $sleepInterval
$file = Get-ChildItem -Path $env:temp -Filter "*$fileName"|Select -First 1
}While(!$file -and $sleepElapsed -le $sleepTime)
$file.FullName
}
That lets you define things like sleep settings at runtime if you want, or just let it default to what you were using, same with the file name. Then it downloads the file, and looks for it, pausing between attempts, until either it finds the file, or it runs out of time. Then it returns $file.FullName which is either the path to the file if it found one, or nothing if it didn't find a file.
Personally I'd have it return the file object, and just utilize the .FullName property if that's all I wanted later. Usually (not always, but usually) more info returned from a function is better than less info. Like what if the download fails and it's a zero byte file? Just returning only the path doesn't tell you that.