linux check if file is open by another process

Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. Then when your process attempts to acquire a write lock, it will fail if another process has the file open. As a side note: If you wanted to check if the file is already open (by any other process or thread), you can try getting a file write lease ( fcntl (fileno (stream),F_SETLEASE,F_WRLCK) ). Why is category theory the preferred language of advanced algebraic geometry? Does Iowa have more farmland suitable for growing corn and wheat than Canada? Well the easiest way is to keep track of it yourself. how to check if a Java program is keeping open a handle to a file? Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood. I have a file in a Linux system that says has been last accessed by the process that created it a couple of hours ago, but I would like to know if that process has already finished writing into the file, or if the file is now basically finished writing. Why is the Work on a Spring Independent of Applied Force? In this case there are already answers here: No, @2419, the questions you referenced aren't "mine". This is hardly ever used, but if you completely control the system in question, it may be an option. check How can I determine what process has a file open in Linux? Nope. Same mesh but different objects with separate UV maps? How to know if a file is actually opened or closed? lslocks lists information about all the currently held file locks in a Linux system. c windows file Share Improve this question That only works if everybody else uses this code. Or use the proc, procfs or psutil module. int r, fd; r = fcntl ( fd, F_GETFL ); if (r==-1) printf("File %d is closed.\n", fd); if (r>0) printf("File %d is open.\n", fd); If the return value is -1, the file is not open (or fd was not a valid file descriptor). How can I manually (on paper) calculate a Bitcoin public key from a private key? Are Tucker's Kobolds scarier under 5e rules than in previous editions? psutil is cross-platform and has an open_files() method which seems like it would be useful here. directory, jail root directory, active executable text, or kernel trace lsoft is a bit worse resolve because this is working more slowly. Can something be logically necessary now but not in the future? What could be the meaning of "doctor-testing of little girls" by Steinbeck? How "wide" are absorption and emission lines? Compared to using an alternative such as flock, as far as I understand, flock is only advisory, so it will only work if all processes cooperate to check the lock, which is not the case most of the time if the processes are independent. WebYou can use lsof | grep /absolute/path/to/file.txt to see if a file is open. For a file without any other process opening it: $ lsof -f -- ~/.bashrc. It appears to me that there is no portable solution available, yet. Find centralized, trusted content and collaborate around the technologies you use most. 1 Answer. Check if a file is opened by other process without opening it in C (Linux environment). The best answers are voted up and rise to the top, Not the answer you're looking for? it does not work on ubuntu/linux. Geometry Nodes - Animating randomly positioned instances to a curve? This locking is defined in POSIX, and will be portable across operating systems. Count the number of accesses made to a file. I will present my solution tomorrow in this thread. This post does not answer the question posed in the OP. thanks so far! linux bash file-descriptors open-files Share Improve this question Follow edited Dec 28, 2016 at 23:31 You can use @ronomon/opened to check if a file is open in another process, if any applications have open handles or file descriptors to the file. WebOn Linux, one can use the kcmp(2) KCMP_FILE operation to test whether two file descriptors (in the same process or in two different processes) refer to the same open file description. Any issues to be expected to with Port of Entry Process? and then check whether a file is open with: In python, you could use os.walk() and os.readlink() to build a dict. Very useful when you want to copy files over existing ones, and can't overwrite a locked file. Since you know the file, that ought not be a problem. but it works for windows. Unless other application uses advisory locks. For example, on linux, have your program do the following: open up the ~/.mozilla/firefox/ directory. file In linux, you can rename the file while it's open. It works on Windows, macOS and Linux and requires privileges only on Linux. Java - Check if other programs read a file? 589). lslocks reads /proc/locks, in a pinch you can read that directly yourself, with the caveat that files are identified by device and inode rather than name. linux Making statements based on opinion; back them up with references or personal experience. Is there a way to list the currently open file descriptors? What happens if a professor has funding for a PhD student but the PhD student does not come? Does Iowa have more farmland suitable for growing corn and wheat than Canada? Forcing user to clear up the crap after your crashed app is mental. What does Bitcoin Core need to be upgraded to 1.0? But why does this return 1 always? UNIX is a registered trademark of The Open Group. int r, fd; r = fcntl ( fd, F_GETFL ); if (r==-1) printf("File %d is closed.\n", fd); if (r>0) printf("File %d is open.\n", fd); If the return value is -1, the file is not open (or fd was not a valid file descriptor). Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. Just use it with the -p option and a process id (PID) to get the listing: lsof -p [pid] how to find who is holding the lock of a file in RCS. 2 Answers. Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site. close a file) only if you first lock the mutex, do ALL THE WORK, then unlock the mutex. What's the right way to say "bicycle wheel" in German? Find centralized, trusted content and collaborate around the technologies you use most. (Ep. Thanks for contributing an answer to Stack Overflow! Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. So, how can I determine what process has a particular file open in Linux? Any issues to be expected to with Port of Entry Process? Find centralized, trusted content and collaborate around the technologies you use most. The Overflow #186: Do large language models know what theyre talking about? This indicates if "File is already locked in this thread or virtual machine", but I want to know if the file is open by someone. Connect and share knowledge within a single location that is structured and easy to search. Why is that so many apps today require a MacBook with an M1 chip? 589). Is this color scheme another standard for RJ45 cable? @JonathanBen-Avraham Any actual answer to that question is immediately useless - it only tells you if the file, @AndrewHenle The point of my comment is that this post only answers a degenerate case where you 1) have access to the application code 2) can build the code 3) have permission from your management to change the code 3) have a license to change the code 4) it is feasible to re-design to the code without having to re-certify the final system. Good statement. Check US Port of Entry would be LAX and destination is Boston. If your file is not there it means it is not open. It only takes a minute to sign up. In unix you can use fcntl to use file locks. However, you may use lsof to check whether the file is opened by any other processes. This is valid for any kind of resources, not just files. only one thread can open file filename) then you need to have a my_file_open() function which locks, searches, adds a new my_file if not found, then return that new added my_file pointer. WebIf you want to know which exact process's file descriptor links to your file without lsof or fuser search thru /proc: $ find /proc -regex '\/proc\/[0-9]+\/fd\/. Programs like cp will close the file after the work is done. The Overflow #186: Do large language models know what theyre talking about? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. The $ lsof answer by @fin is the best answer, obviously, but to answer @JoseLSeguras comment, if this isn't available, the solution above was my response. If the file is open, this command will return status 0, otherwise it will return 256 (1). Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood, How to list the open file descriptors (and the files they refer to) in my current bash session, How to display open file descriptors but not using lsof command. another thread is already using it). In Indiana Jones and the Last Crusade (1989), when does this shot of Sean Connery happen? Java - Check if other programs read a file? Since you know the file, that ought not be a problem. fuser has strange behavior with exit codes. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Pros and cons of "anything-can-happen" UB versus allowing particular deviations from sequential progran execution, The shorter the message, the larger the prize, Proving that the ratio of the hypotenuse of an isosceles right triangle to the leg is irrational. File file = new File (fileName); FileChannel channel = new RandomAccessFile (file, "rw").getChannel (); FileLock lock = channel.lock (); try { lock = channel.tryLock (); // Ok. Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood. For your purpose, use the F_GETFL flag as in. Linux is a registered trademark of Linus Torvalds. However, you may use lsof to check whether the file is opened by any other processes. Is it legal for a brick and mortar establishment in France to reject cash as payment? By clicking Post Your Answer, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct. Find centralized, trusted content and collaborate around the technologies you use most. Making statements based on opinion; back them up with references or personal experience. Why is category theory the preferred language of advanced algebraic geometry? C++ | Windows - Is there a way to find out which process has ownership of the locked file? How is the pion related to spontaneous symmetry breaking in QCD? However, you may use lsof to check whether the file is opened by any other processes. This is exactly what I was looking for. Information about a process is in the directory /proc/. How can I tell if a file is open elsewhere in C on Linux? Here is a FANTASTIC resource. Which field is more rigorous, mathematics or philosophy? By clicking Post Your Answer, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct. The example bash algorithm above doesn't, all it does is note the fact that a filename is opened by something. How can I find out which object has a file open in Java? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. It only takes a minute to sign up. What doesn't work? Here the psutil method that works for me, but is too slow (~10 Seconds). More on Linux locks here. In python how can i know a given file is being used, Check to see if file is open before doing anything, How to tell if a file is in use by another application in Python on Windows, How to check if a file is already opened (in the same process), Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing, Hi @JimBlack, thanks, but theres no lsof library i can try in pycharm (im not using a linux server, sorry for that) but lsof is in the psutil library which is, for me, too slow (takes around 20 seconds for every file to check). What is the relational antonym of 'avatar'? The fuser Unix command will give you the PIDs of the processes accessing a file. Adding labels on map layout legend boxes using QGIS, Denys Fisher, of Spirograph fame, using a computer late 1976, early 1977. If no options are specified, fstat reports on all open files in the system. What is the state of the art of splitting a binary file by size? If the file is open, this command will return status 0, otherwise it will return 256 (1). How "wide" are absorption and emission lines? What is the relational antonym of 'avatar'? Creating and manually managing your own mutexes offers you more flexibility than you would otherwise have. I need that check for Visual C++ / Windows though. If the file exists (and is read only) the file creation will fail, so you get check-and-lock in a single atomic operation. The kernel keeps the data under /proc. Excel Needs Key For Microsoft 365 Family Subscription. Stack Exchange network consists of 182 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. How can I determine what process has a file open in Linux? This works fine for OSX, but is not compatible with Node 6 in Windows. Should I include high school teaching activities in an academic CV? What result do you get from the code you provided here? from subprocess import check_output, Popen, PIPE src = r"C:\Data\S_t_h\S-t-h\H001.mdf" files_in_use = False def file_in_use(src): try: lsout = Popen(['lsof', src], stdout=PIPE, shell=False) check_output(["grep", src], stdin=lsout.stdout, shell=False) except: return 589). On most Linux systems lsof NAME does the job: Having a file open is not a lock because, if each process has to check whether the file is open first and not proceed if it is or create/open it if it isn't, then two processes could quite well check simultaneously, both find that it isn't open, then both create or open it. file Perhaps, a user process can get access to these records in the kernel? *' -type l -lname "*$1*" -printf "%p -> %l\n" 2> /dev/null Replace $1 with the open filename you are searching for. Adding labels on map layout legend boxes using QGIS. Is there any way to open a file with non-sharing exclusive read-write access? WebYou can use lsof | grep /absolute/path/to/file.txt to see if a file is open. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. Denys Fisher, of Spirograph fame, using a computer late 1976, early 1977. Programs like cp will close the file after the work is done. linux linux I know, that there's the is_open() function in C++, but I want one program to check if a file hasn't been opened by another application.

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