Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. We accomplish this by creating thousands of videos, articles, and interactive coding lessons - all freely available to the public. There has one thread will regularly record some logs in file. Create timezone aware datetime object in Python. This can be used when the file that you are trying to open is in the same directory or folder as the Python script, like this: But if the file is within a nested folder, like this: Then we need to use a specific path to tell the function that the file is within another folder. Why are non-Western countries siding with China in the UN? We have a line that tries to read it again, right here below: This error is thrown because we are trying to read a closed file. There are many ways to customize the try/except/finally statement and you can even add an else block to run a block of code only if no exceptions were raised in the try block. This is Windows specific, the question being about Excel then it makes sense, but not in every scenario this will be true. The "a" mode allows you to open a file to append some content to it. Awesome, right? You could check a file, decide that it is not in use, then just before you open it another process (or thread) leaps in and grabs it (or even deletes it). How to print and connect to printer using flutter desktop via usb? Not exactly, but not too far. How to get path from filedialog currently open, Block execution until a file is created/modified, Edit file being processed by python script. The first step is to import the built-in function using the import os.path library. Further on, when the loop is run, the listdir function along with the if statement logic will cycle through the list of files and print out the results, depending on the conditions passed within the print statement. # if the initial hash is equal to the final hash, the file not changed, # generate a hash if it's a file and add it to the output list, # return False if any files are found to be in use, # generate hashed for all files in a sub-directory, add the output to the list, # if the initial list is equal to the final list, no files in the directory. source: http://docs.python.org/2.4/lib/bltin-file-objects.html. You can work with this list in your program by assigning it to a variable or using it in a loop: We can also iterate over f directly (the file object) in a loop: Those are the main methods used to read file objects. The next command checks if the file exists on the specific location. Looking for connections in the world of IT? To provide the best experiences, we and our partners use technologies like cookies to store and/or access device information. "Appending" means adding something to the end of another thing. This is how you could do that: To wait a specified amount of time you can make use of the sleep() method which can be imported from the time module. In this case, .txt indicates that it's a text file. 2. As in my system many chrome instances are running. One of the most important functions that you will need to use as you work with files in Python is open(), a built-in function that opens a file and allows your program to use it and work with it. Here's an example. This is basically telling us that a file object is an object that lets us work and interact with existing files in our Python program. Usage of resources like CPU, memory, disks, network, sensors can be monitored. They are slightly different, so let's see them in detail. Critical issues have been reported with the following SDK versions: com.google.android.gms:play-services-safetynet:17.0.0, Flutter Dart - get localized country name from country code, navigatorState is null when using pushNamed Navigation onGenerateRoutes of GetMaterialPage, Android Sdk manager not found- Flutter doctor error, Flutter Laravel Push Notification without using any third party like(firebase,onesignal..etc), How to change the color of ElevatedButton when entering text in TextField, Pandas dataframe to excel: AttributeError: 'list' object has no attribute 'to_excel', how to set a column to DATE format in xlsxwriter, sheet.nrows has a wrong value - python excel file. this is extremely intrusive and error prone. Lets iterate over it and print them i.e. Is there a way to check if a file is in use? Tip: A module is a Python file with related variables, functions, and classes. Weapon damage assessment, or What hell have I unleashed? Has Microsoft lowered its Windows 11 eligibility criteria? Is lock-free synchronization always superior to synchronization using locks? how can I do it? Making statements based on opinion; back them up with references or personal experience. To handle these exceptions, you can use a try/except statement. Python's os.path.isfile () method can be used to check a directory and if a specific file exists. Drift correction for sensor readings using a high-pass filter. Thanks for contributing an answer to Stack Overflow! Every developer understands the need to create fall back codes, which can save a prorgram from failing in the case that a condition isn't met. Requires two file paths as . As per the existence of the file, the output will display whether or not the file exists in the specified path. The fstat utility identifies open files. Check if a file is not open nor being used by another process, Need a way to determine if a file is done being written to, Ensuring that my program is not doing a concurrent file write. Acceleration without force in rotational motion? Flutter change focus color and icon color but not works. On Linux it is fairly easy, just iterate through the PIDs in /proc. Why does awk -F work for most letters, but not for the letter "t"? import os.path os.path.isfile (r "C:\Users\Wini Bhalla\Desktop\Python test file.txt") For this example, we'll measure the initial size of the file, wait 2 seconds, then measure it again and compare the two sizes to see if it changed. There is a sysinternals tool (handle.exe) that can be used, but I recommend the PyPi module psutil, which is portable (i.e., it runs on Linux as well, and probably on other OS): Will your python script desire to open the file for writing or for reading? I can not include the other thirdparty packages. Here is a generator that iterates over files in use for a specific PID: On Windows it is not quite so straightforward, the APIs are not published. Much rather have his message and yours than neither. And have some results: I tried this code, but it doesn't work, no matter i use "r+" or "a+" flag. Here's the code: You can check if a file has a handle on it using the next function (remember to pass the full path to that file): I know I'm late to the party but I also had this problem and I used the lsof command to solve it (which I think is new from the approaches mentioned above). To be able to read a file and perform another operation in the same program, you need to add the "+" symbol to the mode, like this: Very useful, right? Without a subpoena, voluntary compliance on the part of your Internet Service Provider, or additional records from a third party, information stored or retrieved for this purpose alone cannot usually be used to identify you. You could use with open("path") as file: so that it automatically closes, else if it's open in another process you can maybe try But, sorry i can not try to install the psutil package. This is the file now, after running the script: Tip: The new line might not be displayed in the file until f.close() runs. Creating an MD5 hash of the entire file before and after a predetermined polling period can tell whether a file has been modified with a high amount of accuracy. then the problem's parameters are changed. the legacy application is opening and closing the file every X minutes, but I do not want to assume that at t = t_0 + n*X + eps it already closed the file. Why was the nose gear of Concorde located so far aft? Consider this code: if not-in-use: use-the-file This is posted as an answer, which it is not. :). Tip: These are the two most commonly used arguments to call this function. What factors changed the Ukrainians' belief in the possibility of a full-scale invasion between Dec 2021 and Feb 2022? If you are working with files that are larger than just a few megabytes, you could run in to issues such as high CPU usage, long wait times or running out of memory entirely. os.rename(---); os.rename(---); print "Access ---" You should also catch KeyboardInterrupt and SystemExit exceptions so you can attempt to restore the filename before the application quits. The print should go after. Is there any way can do this by using pure python2.4? The function shows False for an invalid path. The multiprocessing package offers both local and remote concurrency, effectively side-stepping the Global Interpreter Lock by using subprocesses instead of threads. attempting to find out what files are open in the legacy application, using the same techniques as, you are even more vulnerable to race conditions than the OS-independent technique, it is highly unlikely that the legacy application uses locking, but if it is, locking is not a real option unless the legacy application can handle a locked file gracefully (by blocking, not by failing - and if your own application can guarantee that the file will not remain locked, blocking the legacy application for extender periods of time. I want to open a file which is periodically written to by another application. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. How to react to a students panic attack in an oral exam? If no options are specified, fstat reports on all open files in the system. If you read this far, tweet to the author to show them you care. Something like, http://docs.python.org/2.4/lib/bltin-file-objects.html. Is there a way to check if the current file has been opened by another application? I really hope you liked my article and found it helpful. You could check a file, decide that it is not in use, then just before you open it another process (or thread) leaps in and grabs it (or even deletes it). To subscribe to this RSS feed, copy and paste this URL into your RSS reader. There are six additional optional arguments. In Python, there are several ways to check if a file exists; here are the top methods you should know about. You have two ways to do it (append or write) based on the mode that you choose to open it with. You can solve your poblem using win32com library. @Ioannis Filippidis - If he hadn't given his answer, you wouldn't have been able to deliver your message. Is there a way to check if file is already open? But if the user forgets to close the file before any further writing, a warning message should appear. closing the file every X minutes, but Tip: The file will be initially empty until you modify it. To see if anything has changed in the directory, all you need to do is compare the output of this function over a given interval just as we did in the first two examples. So it will return True. import psutil for proc in psutil.process_iter (): try: # this returns the list of opened files by the current process flist = proc.open_files () if flist: print (proc.pid,proc.name) for nt in flist: print ("\t",nt.path) # This catches a race condition where a process ends # before we can examine its files except psutil.NoSuchProcess as err: print If favouring the "check whether the legacy application has the file open" (intrusive approach prone to race conditions) then you can solve the said race condition by: Updated NOTE on this solution: Checking with FileAccess.ReadWrite will fail for Read-Only files so the solution has been modified to check with FileAccess.Read. os.path.exists (path) Parameter. How to upgrade all Python packages with pip. The md5() function generates a hash using a given string, then we can retrieve that hash using the hexdigest() or digest() function, the only difference between those two functions is that hexdigest() returns the hash in the form of hexadecimals instead of bytes. To learn more about them, please read this article in the documentation. To update all Python packages on Linux, you can use the following command in the command line: sudo pip install --upgrade pip && sudo pip freeze --local grep -v '^\-e' cut -d = -f 1 xargs -n1 sudo pip install -U. Learn how to detect whether a given file is being copied or currently being modified/written to using pure Python. There is a sysinternals tool (handle.exe) that can be used, but I recommend the PyPi module psutil, which is portable (i.e., it runs on Linux as well, and probably on other OS): I like Daniel's answer, but for Windows users, I realized that it's safer and simpler to rename the file to the name it already has. check if a file is open in Python python excel 187,716 Solution 1 I assume that you're writing to the file, then closing it (so the user can open it in Excel), and then, before re-opening it for append/write operations, you want to check that the file isn't still open in Excel? The syntax is as follows: os.popen (command [, mode [, bufsize]]) Here the command parameter is what you'll be executing, and its output will be available via an open file. As expected, the use of this syntax returns a boolean value based on the existence of directories. "C:\Users\Wini Bhalla\Desktop\Python test file.txt", "C:\Users\Wini Bhalla\Desktop\testdirectory", try and except statement checks a command, Learning Python? This is the basic syntax to call the write() method: Tip: Notice that I'm adding \n before the line to indicate that I want the new line to appear as a separate line, not as a continuation of the existing line. directory, jail root directory, active executable text, or kernel trace multiprocessing is a package that supports spawning processes using an API similar to the threading module. Here's a Python decorator that makes using flock easier. By using them, you don't need to remember to close a file at the end of your program and you have access to the file in the particular part of the program that you choose. Share. If Pythons processor is able to locate the file, it will open the file and print the result File is open and available for use. 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