[SOLVED] Error renaming text files based on the first line in the file in Powershell

Error renaming text files based on the first line in the file in Powershell

I'm trying to rename a large number of plain text files based on the first line. The issue I'm encoutering is that some first lines have invalid characters (illegal characters in path) so I get errors. This is what I'm using:

$files = Get-ChildItem *.txt

$file_map = @()
foreach ($file in $files) {
    $file_map += @{
        OldName = $file.Fullname
        NewName = "{0}.txt" -f $(Get-Content $file.Fullname| select -First 1)
    }
}

$file_map | % { Rename-Item -Path $_.OldName -NewName $_.NewName }

Is there a way to ignore special characthers when renaming?

Thanks.

Solution

The following might work for you. Essentially, you can use the Path.GetInvalidFileNameChars Method to get a char array of those invalid characters for a file name then create a regex pattern to remove those invalid chars:

$invalidChars = ([IO.Path]::GetInvalidFileNameChars() |
    ForEach-Object { [regex]::Escape($_) }) -join '|'

Get-ChildItem *.txt | Rename-Item -NewName {
    $firstLine = ($_ | Get-Content -TotalCount 1) -replace $invalidChars
    '{0}.txt' -f $firstLine
}

Perhaps an easier approach would be to remove any Non-word character with \W:

Get-ChildItem *.txt | Rename-Item -NewName {
    $firstLine = ($_ | Get-Content -TotalCount 1) -replace '\W'
    '{0}.txt' -f $firstLine
}

Or to remove any character that is not in the character ranges a-z, A-Z, 0-9 or a space :

Get-ChildItem *.txt | Rename-Item -NewName {
    $firstLine = ($_ | Get-Content -TotalCount 1) -replace '[^a-z0-9 ]'
    '{0}.txt' -f $firstLine
}