Monday, June 30, 2008

Scripting Mistake

This evening, a scripting mistake led me to learn about a feature in Systintenals' Process Explorer that I had not previously known about. I subscribe to Mark's blog (listed in the System Administration blogs) and he writes a series titled, "The Case of..." where he details his troubleshooting process for a specific issue. In his post, The Case of the System Process CPU Spikes, he demonstrated pretty cool uses of Process Explorer -- since I read that post in April, I've been running Process Explorer in my little tray just like he described in his post. Occasionally I find uses for it like closing stale processes -- but I've never REALLY used it until tonight.

Earlier, I wanted utilize robocopy to synchronize my local caches of the Systinternals' tools from file:// I maintain two copies: one on my OS drive and one on my thumb drive. My purpose for this is is that I want these tools immediately available when I want to run them -- and while the live share is nice, it takes a few seconds to load.

So I wrote a simple batch script; and made a rudimentary scripting mistake: I wrote a batch script titled robocopy.bat and attempted to call the robocopy executable without specifying it's full path. Here is my original script:

So, this mistake led to some Windows Command Processor crashes:

Interesting right? The infinite loop caused CMD.exe to crash (I guess it's time to install PowerShell and actually read those powershell books on my bookshelf.) When CMD crashed, I went to edit the batch script but wasn't able to save modifications:

OK. I figured that cmd.exe had a lock on the handle -- and I remembered that OpenedFilesView wouldn't work in Vista x64, I didn't feel like downloading a utility and I certainly didn't feel like logging out.

Somehow, I ended up searching for the file handle with Process Explorer's handle or DLL search feature.

After closing the handle, I was able to save modifications to the batch script.

Finally, I fixed my script to call the robocopy executable by it's absolute full path:


I'm glad I learned about the file handle search feature in Process Explorer -- this utility is incredible. Thanks Sysinternals.

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