Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. Geometry Nodes - Animating randomly positioned instances to a curve? The advantage of scanning /proc is that it is backed by direct kernel calls, not a physical file system. How do I find out what process has a lock on a file in Linux? Does Iowa have more farmland suitable for growing corn and wheat than Canada? Multiplication implemented in c++ with constant time. In my case, this example always returns 'file has not been opened' even though file is opened. What is the state of the art of splitting a binary file by size? In this case there are already answers here: No, @2419, the questions you referenced aren't "mine". rev2023.7.17.43535. How to check if a file is used by another process in C++? Just remember that you can't unlock the mutex between the search and the add. In C++, how to detect that file has been already opened by own process? A more cleaner and faster way for this usage of. though I don't need to use it, I'm paying the price of collecting it. how to check if a Java program is keeping open a handle to a file? Can something be logically necessary now but not in the future? (Ep. but I also need to detect when a particular file is closed again to unlock it, so that other users may edit it again. If the file is open, this command will return status 0, otherwise it will return 256 (1). even running the bash while/read loop below only took about 1.5 seconds on my ancient AMD Phenom-II 1090T with ~1000 processes currently running. a vector. linux To learn more, see our tips on writing great answers. [duplicate]. 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. Check if a file is available (not used by another process) in Python. If the file exists (and is read only) the file creation will fail, so you get check-and-lock in a single atomic operation. How terrifying is giving a conference talk? I write in Perl. I am working on a multithreaded system where a file can be shared among different threads based on the file access permissions. basically I tried everything from this question: Check if a file is not open nor being used by another process, and im getting: 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. In linux, you can rename the file while it's open. and look at dwShareMode, value of 0, as well as the other parameters. Do any democracies with strong freedom of expression have laws against religious desecration? How would life, that thrives on the magic of trees, survive in an area with limited trees? This locking is defined in POSIX, and will be portable across operating systems. I have created some file descriptors, using exec, and I would like to list what is the current status of my bash session. How to detect if file is openned by other process in windows. linux lslocks lists information about all the currently held file locks in a Linux system. 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. If no options are specified, fstat reports on all open files in the system. Concurrent Updation to shared output-file (.xls, .csv etc) from different PCs using node.js. Does Iowa have more farmland suitable for growing corn and wheat than Canada? Solution: Linux `lsof` command: list open process files Thats where the lsof command comes in. open WebThe best way to do this is to look for Firefox's lock files. Programs like cp will close the file after the work is done. The shorter the message, the larger the prize. C++ How do I make it so my program wouldn't delete files that are in use? Adding labels on map layout legend boxes using QGIS. linux No particular value for these indicates open/closed. process Blocked entries have a -> prefix before the lock type column (thus adding a column to that line). I have a folder with subfolder and files in it. and it might not be worth implementing because anyone who wants such a list can always trawl through /proc like. See http://docs.sun.com/app/docs/doc/816-0213/6m6ne37v5?a=view. If the return value is -1, the file is not open (or fd was not a valid file descriptor). 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. 589). psutil is cross-platform and has an open_files() method which seems like it would be useful here. rev2023.7.17.43535. Find out all the different files from two different paths efficiently in Windows (with Python), Distances of Fermat point from vertices of a triangle. Linux: How to find files open by a Linux process (lsof 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. How to determine if file is in use by another process (Java). For a file without any other process opening it: $ lsof -f -- ~/.bashrc. It would be nice to also support Linux. the filesystem let me acquire the lock even if the file is already open in another process. In Linux, you can use the utility lsof to see what files are opened by other processes. Thanks for contributing an answer to Stack Overflow! 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. One could introduce a timeout delay but that's just too brittle and arbitrary. On windows I use this simple trick: I know that unix based systems allow to open files in multiple processes Is there a similar trick to achieve the same result for unix based systems ? What is the state of the art of splitting a binary file by size? The fuser Unix command will give you the PIDs of the processes accessing a file. Wouldn't you know how to solve? linux However, you may use lsof to check whether the file is opened by any other processes. Be aware that this command will take a second since there are, normally, a lot of files open at any time. 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. @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. process Non-natively, you could call out to Sysinternals' handle.exe as a last resort As @Neil Butterworth says, the standard library doesnt. What's it called when multiple concepts are combined into a single problem? Why can you not divide both sides of the equation, when working with exponential functions? 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. Should I include high school teaching activities in an academic CV? You could (on linux) check /proc/*/fd but it is possible that your program does not have permission to do it on processes from other users (this is the default in Ubuntu, for instance). The Overflow #186: Do large language models know what theyre talking about? Ask Question Asked 13 years, 6 months ago Modified 3 years, 5 months ago Viewed 38k times 15 I see that standard C has no way of telling if a file is already opened in another process. If the return value is positive, fd describes an open file. c windows file Share Improve this question Unfortunately, it will also affect other processes if they are trying to place lock on our file. Blocked entries have a -> prefix before the lock type column (thus adding a column to that line). If it appears at all it means it's open. You can use int flock(int fd, int operation); to mark a file as locked and also to check if it is locked. No particular value for these indicates open/closed. Check if a file is opened by another application in C? In Linux, you can use the utility lsof to see what files are opened by other processes. You should use the fstat command, you can run it as user : The fstat utility identifies open files. You can achieve this in a Unix filesystem by creating a file with read-only mode and removing it to unlock. The best way that I found is to call the WinAPI CreateFile to open a given file in exclusive mode. Find out all the different files from two different paths efficiently in Windows (with Python), Result of numerical computation representing a real physical quantity still contains a small imaginary components. US Port of Entry would be LAX and destination is Boston. What is Catholic Church position regarding alcohol? c windows file Share Improve this question In the end, I used lsof (list open files) and grepped its output to find the offending process: To subscribe to this RSS feed, copy and paste this URL into your RSS reader. If no options are specified, fstat reports on all open files in the system. How is the pion related to spontaneous symmetry breaking in QCD? What is the motivation for infinity category theory? Any issues to be expected to with Port of Entry Process? Check if a file is not open nor being used by another process. if a security manager exists and its checkRead method denies read access to the file or the mode is "rw" and the security manager's checkWrite method denies write access to the file. The Overflow #186: Do large language models know what theyre talking about? What result do you get from the code you provided here? How would you get a medieval economy to accept fiat currency? file It works on Windows, macOS and Linux and requires privileges only on Linux. file for that process. Sorry for the delayed answer. 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. This works fine for OSX, but is not compatible with Node 6 in Windows. It always returns false. Opening a new process with lsof and reading out the standard output will do the job. I need that check for Visual C++ / Windows though. This isn't as "heavy" as you think. linux I can always lock file, even if file is being written!!! Are Tucker's Kobolds scarier under 5e rules than in previous editions? Any issues to be expected to with Port of Entry Process? Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood. Is this color scheme another standard for RJ45 cable? fuser has strange behavior with exit codes. Here's a sample how to use lsof for unix based systems: This one should also work for Windows systems. The easiest thing is to keep a shared list of all opened files, and make it available to all threads. How do I write the reference mark symbol in TeX? Any issues to be expected to with Port of Entry Process? Way to check in C/C++ if a file is in use? Adding salt pellets direct to home water tank. Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood. Python - How to check if a file is used by another application? The best way that I found is to call the WinAPI CreateFile to open a given file in exclusive mode. The Overflow #186: Do large language models know what theyre talking about? This is limited to what you have permissions for - you have to do the check as a privileged user, or you'll only get results for files opened by the same user as the one doing the check. Why does tblr not work with commands that contain &? What does a potential PhD Supervisor / Professor expect when they ask you to read a certain paper? lslocks lists information about all the currently held file locks in a Linux system. How would I know that file is opened and it is saved after some writing operation using C code? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Process linux In Linux, you can use the utility lsof to see what files are opened by other processes. Linux: How to find files open by a Linux process (lsof Why was there a second saw blade in the first grail challenge? Bass line and chord mismatch - Afternoon in Paris. +1 I've been looking for an app which does exactly what handle.exe does. Why was there a second saw blade in the first grail challenge? If the file is open, this command will return status 0, otherwise it will return 256 (1). 2 Answers. I try to find a solution for the following problems but can't find any good solution. (part of util-linux) this utility has support for json output, which is nice for scripts. Since you know the file, that ought not be a problem. Denys Fisher, of Spirograph fame, using a computer late 1976, early 1977. 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. Learn more about Stack Overflow the company, and our products. Why does tblr not work with commands that contain &? Among the columns are PID (the process id of the program that has the file open) and the FD (the file descriptor associated with the open file). process It only takes a minute to sign up. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. How should a time traveler be careful if they decide to stay and make a family in the past? a vector, Bass line and chord mismatch - Afternoon in Paris. In Indiana Jones and the Last Crusade (1989), when does this shot of Sean Connery happen? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, The future of collective knowledge sharing. (Ep. file Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood. The Overflow #186: Do large language models know what theyre talking about? file Check Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. For a file without any other process opening it: $ lsof -f -- ~/.bashrc. Thanks for contributing an answer to Stack Overflow! To use a file as a lock, the check-and-lock operation has to be a single uninterruptable operation. Do any democracies with strong freedom of expression have laws against religious desecration? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. No particular value for these indicates open/closed. When a customer buys a product with a credit card, does the seller receive the money in installments or completely in one transaction? Filesystem to share disks between Linux and FreeBSD, FreeBSD-11 Mate desktop file browser unable to connect to https webdav url, How to check if process with pid X is the one you expect. you're absolutely right but I need this functionality to monitor the file state (which I do with WatchServices in Java 7). Today I had the problem that I couldn't delete a folder because "it was busy". Thanks for contributing an answer to Stack Overflow! Why can you not divide both sides of the equation, when working with exponential functions? What does a potential PhD Supervisor / Professor expect when they ask you to read a certain paper? What's the significance of a C function declaration in parentheses apparently forever calling itself? (Ep. Seeing you have tagged linux -> there's a command-line too and API that have been added to the Linux kernel and do just that: inotify. Connect and share knowledge within a single location that is structured and easy to search. I have created some file descriptors, using exec, and I would like to list what is the current status of my bash session. Can you elaborate on your problem? What does "rooting for my alt" mean in Stranger Things? Just use it with the -p option and a process id (PID) to get the listing: lsof -p [pid] In Indiana Jones and the Last Crusade (1989), when does this shot of Sean Connery happen? 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. linux Should I include high school teaching activities in an academic CV? For example, on linux, have your program do the following: open up the ~/.mozilla/firefox/ directory. (Ep. rev2023.7.17.43535. If your file is not there it means it is not open. What is the relational antonym of 'avatar'? Be aware that this command will take a second since there are, normally, a lot of files open at any time. lslocks lists information about all the currently held file locks in a Linux system. Check I'd suggest using fuser over lsof. Is this subpanel installation up to code? Why does this journey to the moon take so long? I only know of the command line utility, not of any system call you can use directly from C code. So the answer should contain several examples for each platform. 589). C++ how to check if file is in use - multi-threaded multi-process system, How to check if a file is already opened in C. Check if a file is opened by another application in C? Your code doesn't make sense. rev2023.7.17.43535. You will still be able to open the file even if it is in use. How do I write the reference mark symbol in TeX? 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. That only works if everybody else uses this code. You might also take advantage of any file-locking features offered inherently or explicitly by the OS (ex: fcntl). First, declare the following Local External Function (PB10) FUNCTION Long CreateFile (ref string lpszName, long fdwAccess, long fdwShareMode, long lpsa, & long fdwCreate, long fdwAttrsAndFlags, long hTemplateFile) LIBRARY unix.stackexchange.com/questions/333186/, How terrifying is giving a conference talk? The lsof (list open files) command can be used to list files that are opened by a specified Linux process. linux bash file-descriptors open-files Share Improve this question Follow edited Dec 28, 2016 at 23:31 See here linux NFS There are many infelicities in the protocol underlying NFS, affecting amongst others O_SYNC and O_NDELAY . method denies read access to the file or the mode is "rw" and the Why does this journey to the moon take so long? Parsing the results will be much simpler. If you need to open the file in a safe manner (i.e. I tried also to use the tryLock(). Connect and share knowledge within a single location that is structured and easy to search. Most appropriate model for 0-10 scale integer data. How to check if a file is already open by another process in C? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. What does "rooting for my alt" mean in Stranger Things? Check Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood. So, how can I determine what process has a particular file open in Linux? dF. @Waslap. 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. It only takes a minute to sign up. Most appropriate model for 0-10 scale integer data. It contains entries for everything opened by the process file, named by its file descriptor, which is linked to the actual file. What does "rooting for my alt" mean in Stranger Things? process Connect and share knowledge within a single location that is structured and easy to search. Linux - Will the CP command overwrite an open file. Note: your Java program won't be portable in this case, contradicting the portability concept, so think twice whether you really need this :). Starting the Prompt Design Site: A New Home in our Stack Exchange Neighborhood. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Why was there a second saw blade in the first grail challenge? Be aware that this command will take a second since there are, normally, a lot of files open at any time. if a security manager exists and its checkRead method denies read access to the file or the mode is "rw" and the security manager's checkWrite method denies write access to the file. If no options are specified, fstat reports on all open files in the system. C++ | Windows - Is there a way to find out which process has ownership of the locked file? How to show hidden files (. rev2023.7.17.43535. How can I tell if a file is open elsewhere in C on Linux? How can I tell wheter a file is opened by an other application? What is the relational antonym of 'avatar'? Learn more about Stack Overflow the company, and our products. How to check whether the files is being used by another program, Reading files in Java which might be modified by another process. This is the next thing I will try to do. linux Browse other questions tagged. open Derivative of cross product w.r.t. A file is considered open by a process if it was explicitly opened, is the working directory, root directory, jail root directory, active executable text, or kernel trace file for that process. Temporary policy: Generative AI (e.g., ChatGPT) is banned, Make sure file is not opened in Java with without triggering exception if not created, Check if file or folder is open before delete. How terrifying is giving a conference talk? If you don't have root, you likely don't have privs to find out if another user has the file open anyhow. 589). 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\/. flock should work in a threaded app if you open the file separately in each thread: Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Preferably a one-liner type or a particular Linux tool solution would be optimal. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. check Programs like cp will close the file after the work is done. The program below sketches out a solution: From your comment, it seems what you want to do is to retrieve an existing FILE * if one has already been created by a previous call to fopen() on the file. Find out all the different files from two different paths efficiently in Windows (with Python). Pros and cons of "anything-can-happen" UB versus allowing particular deviations from sequential progran execution. 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. It does a lot more than what you need for this job. 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). With one process openning for reading: Doping threaded gas pipes -- which threads are the "last" threads? this doesn't seem to work for files, only for dirs. Deutsche Bahn Sparpreis Europa ticket validity. How would you get a medieval economy to accept fiat currency? There isn't, AFAIK, a standard system call to find this infoso you need some native, per-OS code to do it. Since you know the file, that ought not be a problem. Check if a file is open in another process, github.com/baudehlo/node-fs-ext/issues/57, How terrifying is giving a conference talk? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. If your locking process is a shell script that will be running as a daemon, you can get this effect by using umask, a per-process setting that sets the permissions that new files are created with: ls -l /proc/*/cwd | grep '/var/lock/foo$', ls -l /proc/*/cwd 2>/dev/null | grep '/var/lock/foo$'. Thanks for contributing an answer to Stack Overflow! Process [Java]How to determine whether a file is using? You will still be able to open the file even if it is in use. WebYou can use lsof | grep /absolute/path/to/file.txt to see if a file is open. 589). How to check whether the file is using/reading or not in JAVA? So the answer should contain several examples for each platform. Derivative of cross product w.r.t. Connect and share knowledge within a single location that is structured and easy to search. This is essentially the same pattern that. thanks a lot for your solution. Are there websites on which I can generate a sequence of functions? rev2023.7.17.43535. A file is considered open by a process if it was explicitly opened, is the working directory, root directory, jail root directory, active executable text, or kernel trace file for that process. Information about a process is in the directory /proc/. Why is that so many apps today require a MacBook with an M1 chip? Use lsof to find out what has what files are open. It would be better if fuser will exit with three codes, not two like currently.
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