determining file changes in python - python

I have a text file being written by another process on a server which I want to watch for changes. Each time a change occurs I'd like to read the new data and send it to client .
Any suggestions will be valuable . Using Django,Python
Tazim.

If you're using a recent Linux you should look into this:
http://trac.dbzteam.org/pyinotify
How do I watch a file for changes?
goes into details for win32

On Linux a convenient interface for file modification monitoring is Gamin the File Alteration Monitor. Python bindings are provided and they are really easy to use, though they could be documented better (especially the 'magic numbers' returned).

Related

How can I prevent the filename from changing (rename) using python?

I have a project in mind, but there is a section that I don't know how to do. I'm using Python version 3.6 and windows 10. For example we have a file name of "example.txt" I want to prevent the name and its content of this file from being changed.
I did research on this topic, but I could not reach any research. Can we prevent the file's name (including its extension) from changing or its contents?To realize this, I think it is necessary to start as an administrator.
Thanks.
It is possible to stop another program from editing a file by locking it in python.
There is a module that does this called filelock. Take a look at the source code to see how it is done.
It is also worth noting that more advanced ransomware will try to stop processes so they can encrypt files, so this might not work in all cases.

django/python: How to convert pptx/docx formats to PDF using python?

First of all, I agree that this might sound like a question which has already been asked many times in the past. However I couldn't find any answer that was relevant to me in the similar questions so I'll try to be more specific.
I would need to transform PPTX/DOCX files into PDF using Python but I don't have any experience in file format conversion. I have been looking in many places/forums/websites, read a lot of documentation and came across some useful libraries (python-pptx and pyPdf mainly), but I still don't know where to start.
When looking on the Internet, I can see many websites that offer file format conversions as a paying service, even with advanced API's: submit a file via POST and get the transformed PDF file in return. This could work for me, but I am really interested in writing myself the code that does the conversion work from OOXML to PDF.
How would you start doing this? Or is it just impossible on my own?
Thanks for your help!
After some research and with the help of python-pptx's creator, I was able to write to the PowerPoint COM interface using a Virtual Machine.
In case someone reads this thread, this is how I managed to get this done:
- Setup a VM with Microsoft Windows/Office installed on it ;
- Install Python, Django and win32com libraries on the VM.
The files are sent locally from the original Django project to the virtual machine (which are on the same network) through a simple POST request. The file is converted on the VM using win32com.client (which is just a simple call to the win32com.client library) and then sent back as a response to the original Django view, which in turn processes the response.
Note: it took me some time to realize I needed to use the #csrf_exempt decorator for this setup to work.

Reading a windows file without preventing another process from writing to it

I have a file that I want to read. The file may at any time be overwritten by another process. I do not want to block that writing. I am prepared to manage corruption to the data that I read, but do not want my reading to be in any way change the behaviour of the writing process.
The process that is writing the file is a delphi program running locally on the server. It opens the file using fmCreate. fmCreate tries to open the file exclusively and fails if there are any other handles on the file.
I am reading the file from a python script that accesses the file remotely across our network.
I am interested in whether there is a solution, independent of whether it is supported by python or delphi. I want to know if there is any way of achieving this under windows without modifying the writing program.
Edit: To reiterate, this is not a duplicate. The other question was trying to get read access to a file that is being written to. I want to the writer to have access to a file that I have open for reading. These are different questions (although I fear the answer will be similar, that it can't be done.)
I think the real answer here, all of these years later, is to use opportunistic locks. With this, you can open the file for read access, while telling the OS that you want to be notified if another program wants to access the file. Basically, you can use the file as long as you like, and then back off if someone else needs it. This avoids the sharing/access violation that the other program would normally get, if you had just opened the file "normally".
There is an MSDN article on Opportunistic Locks. Raymond Chen also has a blog article about this, complete with sample code: Using opportunistic locks to get out of the way if somebody wants the file
The key is calling the DeviceIoControl function, with the FSCTL_REQUEST_OPLOCK flag, and passing it the handle to an event that you previously created by calling CreateEvent.
It should be straightforward to use this from Delphi, since it supports calling Windows API functions. I am not so sure about Python. But, given the arrangement in the question, it should not be necessary to modify the Python code. Just make your Delphi code use the opportunistic lock when it opens the file, and let it get out of the way when the Python script needs the file.
Also much easier and lighter weight than a filter driver or the Volume Shadow Copy service.
You can setup a filter driver which can act in two ways: (1) modify the flags when the file is opened, and (2) it can capture the data when it's written to the file and save a copy of the data elsewhere.
This approach is much more lightweight and efficient than volume shadow copy service, mentioned in comments, however it requires having a filter driver. There exist several drivers on the market (i.e. those are products which include a driver and let you write business logic in user mode) yet they are costly and can be an overkill in your case. Still, if you need the thing for private use only, contact me privately for a license for our CallbackFilter.
Update: if you want to let the writer open the file which has been already opened, then a filter which will modify flags when the file is being opened is your only option.

Debugging Python within Ableton Live

How can I see script errors for my python MIDI Remote Scripts in Ableton Live? I've seen references online to a hidden Python console, but no documentation on how to open it, if it would even help me!
Currently I type code, reload the script, and see what happens. If nothing happens, then something is wrong. Very tedious...
Edit: I should also point out that there isn't anything useful in the Log.txt file either, yet that file is being updated.
To debug the control surface, you can define your own log method like so:
def log(self, message):
sys.stderr.write("LOG: " + message.encode("utf-8"))
Usage example:
year = 1999
self.log("I'm gonna party like it's " + str(year))
This will append
21179419 ms. RemoteScriptError: LOG: Tonight I'm gonna party like it's 1999
to your Log.txt.
Also, it may be worth knowing that (at least as of Live 9.1) edited control surface files are recompiled every time you load a new song, no need to restart the application.
EDIT: changed the stderr write method so that it doesn't write two lines and an extra return for every log
I use the log.txt for a ton of debugging. It is a little hard to read, but here's my tips.
log writes top down (new info is on next line) and records all the events, more or less.
If you get an error you will get a large hex looking block - about 20+ lines looking like this:
280 ms. Exception: 0x00495580:0x00000000
Right above that block is the error or what may have thrown the script in the Ableton run time.
As you travel UP from that exception you will see something like a trace.
also - you can use :
self.log_message("STUFF")
to write into the log (there are other methods).
I have seen some log file parsers (real time) in my work. Not tried them yet.
Hope that hleps a little. O was ablt to write a PHP app for the python (yeah, sinful I know). http://modrn.dj/app
For the sake of completeness: on Mac OS X 10.9, the Log.txt file is in
/Users/-username-/Library/Preferences/Ableton/Live 9.1/
The Live 9.1 folder may of course be different for different versions of Live.
Note the Library folder is hidden. It took me a while to figure that out. An easy way to access it with Finder: click the Go menu item, then hold Alt and the Library folder will pop into the menu
what about http://remotescripts.blogspot.com/2010_03_01_archive.html
This has certainly changed over the years with different versions of Ableton Live.
I'm running Live 8 and first tried to get the LiveAPI stuff to spit out debug information: http://post.monome.org/comments.php?DiscussionID=4607&page=1
I started with an older version that didn't work with OSX, reported here: http://code.google.com/p/liveapi/issues/detail?id=4 I don't think the new version includes the telnet console.
SO, the best answer is to find a log file here, which contains debug information on a problematic MIDI Remote Scripts:
Library/Preferences/Ableton/Live 8.2.1/Log.txt
You can also use http://julienbayle.net/ableton-live-9-midi-remote-scripts for Ableton Live 9

How to show list of deleted files in windows file system

I am wondering if it is possible to compile a list of deleted files on a windows file system, FAT or NTFS. I do not need to actually recover the files, only have access to their name and any other accessible time (time deleted, created etc).
Even if I can run a cmd line tool to achieve this it would be acceptable.
The application is being developed in Python, however if another language has the capability I could always create a small component implemented in that language.
Thanks.
This is a very complex task. I woudl look at open-source forensic tools.
You also should analyze the recylcing bin ( not completly deleted file )
For FAT you will not be able to get the first character of a deleted file.
For some deleted files the metadata will be gone.
NTFS is much more complex and time consuming due to the more complex nature of this file system.

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