Once again, it's not rocket science: the main challenge is in error handling and logging. I've written servers like that before, but always in C#, using the System.IO.FileSystemWatcher class. Basically, it monitors a folder and when files appear in it, it takes some action on them, in this case: execute them. The other day I had an idea: a PowerShell Script Server. Using a FileSystemWatcher from PowerShell Using constants for table and column names.Using a FileSystemWatcher from PowerShell.Comparing folder security using PowerShell.Occurs when a file or directory in the specified Path is renamed. Occurs when a file or directory in the specified Path is deleted. Occurs when a file or directory in the specified Path is created. Occurs when a file or directory in the specified Path is changed. Source: (v=vs.110).aspx Appendix B - Table of events you’ll be interested in if you’ve landed here |Renamed|Occurs when a file or directory in the specified Path is renamed.| |Deleted|Occurs when a file or directory in the specified Path is deleted.| |Created|Occurs when a file or directory in the specified Path is created.| |Changed|Occurs when a file or directory in the specified Path is changed.| |Security|The security settings of the file or folder.| |LastWrite|The date the file or folder last had anything written to it.| |LastAccess|The date the file or folder was last opened.| |DirectoryName|The name of the directory.| |CreationTime|The time the file or folder was created.| |Attributes|The attributes of the file or folder.| Appendix A - Table detailing Notify Filters enumeration from MSDN: The above works for copied and moved folders (using instead, NotifyFilters.DirectoryName), although more code is required to trigger events for any files inside the folder. The same applies for moved files but you can also watch the source folder for Deleted events (still using the same NotifyFilter). #A bit more….Where are the events for copying and moving?Ĭopied files will trigger Created events in the destination folder so use NotifyFilters.FileName. Then try out the code in this other gist, demonstrating how you can use Created with NotifyFilters.FileName to get a single event from a new file in a folder. Try out the code in this gist to see the two-event behaviour (just copy a fileinto c:\temp when it’s running). However, using this often leads to multiple events, which is not desirable. Most guides to FileWatcher tend to lead you towards the Changed event. DirectoryName I get two events when I create a new file. In case you missed it in the MSDN documentation, you can combine more than one NotifyFilters member by using the bitwise OR operator like so: Which filters can result in a Created event being triggered?Īnd which filters can result in a Deleted event being triggered? Which filters can result in a Renamed event being triggered? So, what filters can result in a Changed event being triggered? Note that the default values for the NorifyFilter property are LastWrite, FileName and DirectoryName. They can also be helpful in limiting the number of events trigger in some scenarios where complex file operations, or applications like antivirus software cause additional events to be triggered (see above) although you can’t have 100% confidence without some additional defensive coding. These filters determine what you are watching and thus, which events can be triggered. Here, I hope to provide simple guidance on using the NotifyFilter enumeration for those just starting out with FileSystemWatcher. The job can only get harder when also up against a known issues (just search on ) with events firing twice.ĮDIT: See my separate blog post, on a more reliable solution to the ‘two FileSystemWatcher events firing twice problem’. When I first worked with the FileSystemWatcher class I ended up experimenting with combinations of NotifyFilters and event handlers to get the desired result it is not immediately clear, which changes to files and folders, trigger which events.
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