@keegan.towne
To register a callback to execute on a file change in Linux, you can use the inotify
API, which is a Linux kernel subsystem for monitoring file system events. Here's an example of how you can do it using inotify
in C programming language:
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#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <sys/types.h> #include <sys/inotify.h> |
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int fd = inotify_init(); if (fd == -1) { perror("inotify_init"); exit(EXIT_FAILURE); } int wd = inotify_add_watch(fd, "/path/to/file", IN_MODIFY); if (wd == -1) { perror("inotify_add_watch"); exit(EXIT_FAILURE); } |
Replace /path/to/file
with the actual path of the file or directory you want to monitor. IN_MODIFY
is the event mask that specifies the type of events to be monitored (in this case, file modifications).
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char buffer[4096]; ssize_t bytesRead; while (1) { bytesRead = read(fd, buffer, sizeof(buffer)); if (bytesRead == -1) { perror("read"); exit(EXIT_FAILURE); } // Process the events struct inotify_event *event; for (char *ptr = buffer; ptr < buffer + bytesRead; ptr += sizeof(struct inotify_event) + event->len) { event = (struct inotify_event *)ptr; if (event->mask & IN_MODIFY) { printf("File modified: %s ", event->name); // Callback function logic goes here } } } |
The above code reads the events from the inotify file descriptor (fd
) and processes them in a loop. In this example, it prints the name of the modified file. Replace the print statement and add your own callback function logic as needed.
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inotify_rm_watch(fd, wd); close(fd); |
After you're done monitoring the file changes, don't forget to remove the watch using inotify_rm_watch
and close the inotify descriptor with close(fd)
.
Note: This is just a basic example of using inotify
to register a callback on file changes. You can find more information about the inotify
API and its capabilities in the Linux man pages (man 7 inotify
).
@keegan.towne
If you prefer to use a higher-level programming language such as Python, you can achieve the same functionality using the pyinotify
library. Here's an example in Python:
First, you need to install the pyinotify
library if you haven't already:
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pip install pyinotify |
Then you can use the following Python script to monitor file changes:
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import pyinotify class EventHandler(pyinotify.ProcessEvent): def process_IN_MODIFY(self, event): print("File modified:", event.pathname) # Callback function logic goes here wm = pyinotify.WatchManager() handler = EventHandler() notifier = pyinotify.Notifier(wm, handler) wdd = wm.add_watch('/path/to/file', pyinotify.IN_MODIFY) notifier.loop() |
Replace /path/to/file
with the actual path of the file you want to monitor. In the process_IN_MODIFY
method, you can add your callback function logic.
When the file is modified, the process_IN_MODIFY
method will be called, and you can perform your desired actions inside this method.
Don't forget to stop the monitoring and release resources properly when you're done:
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notifier.stop() |
This Python example achieves the same goal as the C program using inotify, but with a higher-level and more Pythonic approach. You can explore the pyinotify
library documentation for more advanced usage and options.