Powershell脚本删除未使用的文件

Question

I'm trying to write a script that removes all files from a given directory, however I don't want to remove files that are currently in use (being viewed, edited, etc.). What I'm finding is that for some file types (.docx, .xlsx, etc.), this works just fine and the .ps1 script fails as expected and moves on. However, some files (.bmp, .txt) can be open and get deleted as well. It looks like certain files are not locked when in-use. I guess my question is a few smaller questions:

1. Is there a way to tell if files are in-use (other than seeing if it's locked)?
2. Is there any definitive way to tell which file types are locked when in-use?
3. Is there a better cmdlet than Remove-Item to use for what I am trying to achieve?

Thanks in advance!

Answer 1

Some applications like Word locks the file wile reading them to avoid it being modified while it's open (usualy in case you want to modify it in ex. Word ). Other applications, like notepad , doesn't.

This is not specific to a filetype (which is just a GUI attribute that has nothing to do with the data inside). It's the application that decides if it wants to lock a file or not. Ex:

• Open a docx file in Word: Access denied (file in use)
• Open a docx file in Wordpad: Success (no lock)

AFAIK it's impossible to detect 100% files being in use by ex. notepad which doesn't lock files.

There are many ways to delete files, but Remove-Item is as good as any of them.

Answer 2

Adding to Frode's point, nothing wrong with remove-item . Normal directory doesn't offer you much. Files hosted via windows file server provides session information might help you identify if a file is being used. If possible, you may implement a smart logic that excludes the files are in use.

In general, I'd recommend a work around that your powershell script check file's LastAccessTime, say, delete everything that hasn't been accessed for 24 hours

Get-ChildItem -path c:\ps | Where-Object {$_.LastAccessTime -lt (get-date).addDays(-1)}

The extreme way of protecting files, is using SCM and don't delete anything checked out. However this is not a friendly solution to average users.