1INOTIFY(7) Linux Programmer's Manual INOTIFY(7)
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6 inotify - monitoring filesystem events
7
9 The inotify API provides a mechanism for monitoring filesystem events.
10 Inotify can be used to monitor individual files, or to monitor directo‐
11 ries. When a directory is monitored, inotify will return events for
12 the directory itself, and for files inside the directory.
13 The following system calls are used with this API:
15 * inotify_init(2) creates an inotify instance and returns a file de‐
17 scriptor referring to the inotify instance. The more recent ino‐
18 tify_init1(2) is like inotify_init(2), but has a flags argument that
19 provides access to some extra functionality.
20 * inotify_add_watch(2) manipulates the "watch list" associated with an
22 inotify instance. Each item ("watch") in the watch list specifies
23 the pathname of a file or directory, along with some set of events
24 that the kernel should monitor for the file referred to by that
25 pathname. inotify_add_watch(2) either creates a new watch item, or
26 modifies an existing watch. Each watch has a unique "watch descrip‐
27 tor", an integer returned by inotify_add_watch(2) when the watch is
28 created.
29 * When events occur for monitored files and directories, those events
31 are made available to the application as structured data that can be
32 read from the inotify file descriptor using read(2) (see below).
33 * inotify_rm_watch(2) removes an item from an inotify watch list.
35 * When all file descriptors referring to an inotify instance have been
37 closed (using close(2)), the underlying object and its resources are
38 freed for reuse by the kernel; all associated watches are automati‐
39 cally freed.
40 With careful programming, an application can use inotify to efficiently
42 monitor and cache the state of a set of filesystem objects. However,
43 robust applications should allow for the fact that bugs in the monitor‐
44 ing logic or races of the kind described below may leave the cache in‐
45 consistent with the filesystem state. It is probably wise to do some
46 consistency checking, and rebuild the cache when inconsistencies are
47 detected.
48 Reading events from an inotify file descriptor
50 To determine what events have occurred, an application read(2)s from
51 the inotify file descriptor. If no events have so far occurred, then,
52 assuming a blocking file descriptor, read(2) will block until at least
53 one event occurs (unless interrupted by a signal, in which case the
54 call fails with the error EINTR; see signal(7)).
55 Each successful read(2) returns a buffer containing one or more of the
57 following structures:
58 struct inotify_event {
60 int wd; /* Watch descriptor */
61 uint32_t mask; /* Mask describing event */
62 uint32_t cookie; /* Unique cookie associating related
63 events (for rename(2)) */
64 uint32_t len; /* Size of name field */
65 char name[]; /* Optional null-terminated name */
66 };
67 wd identifies the watch for which this event occurs. It is one of the
69 watch descriptors returned by a previous call to inotify_add_watch(2).
70 mask contains bits that describe the event that occurred (see below).
72 cookie is a unique integer that connects related events. Currently,
74 this is used only for rename events, and allows the resulting pair of
75 IN_MOVED_FROM and IN_MOVED_TO events to be connected by the applica‐
76 tion. For all other event types, cookie is set to 0.
77 The name field is present only when an event is returned for a file in‐
79 side a watched directory; it identifies the filename within the watched
80 directory. This filename is null-terminated, and may include further
81 null bytes ('\0') to align subsequent reads to a suitable address
82 boundary.
83 The len field counts all of the bytes in name, including the null
85 bytes; the length of each inotify_event structure is thus sizeof(struct
86 inotify_event)+len.
87 The behavior when the buffer given to read(2) is too small to return
89 information about the next event depends on the kernel version: in ker‐
90 nels before 2.6.21, read(2) returns 0; since kernel 2.6.21, read(2)
91 fails with the error EINVAL. Specifying a buffer of size
92 sizeof(struct inotify_event) + NAME_MAX + 1
94 will be sufficient to read at least one event.
96 inotify events
98 The inotify_add_watch(2) mask argument and the mask field of the ino‐
99 tify_event structure returned when read(2)ing an inotify file descrip‐
100 tor are both bit masks identifying inotify events. The following bits
101 can be specified in mask when calling inotify_add_watch(2) and may be
102 returned in the mask field returned by read(2):
103 IN_ACCESS (+)
105 File was accessed (e.g., read(2), execve(2)).
106 IN_ATTRIB (*)
108 Metadata changed—for example, permissions (e.g., chmod(2)),
109 timestamps (e.g., utimensat(2)), extended attributes (setx‐
110 attr(2)), link count (since Linux 2.6.25; e.g., for the tar‐
111 get of link(2) and for unlink(2)), and user/group ID (e.g.,
112 chown(2)).
113 IN_CLOSE_WRITE (+)
115 File opened for writing was closed.
116 IN_CLOSE_NOWRITE (*)
118 File or directory not opened for writing was closed.
119 IN_CREATE (+)
121 File/directory created in watched directory (e.g., open(2)
122 O_CREAT, mkdir(2), link(2), symlink(2), bind(2) on a UNIX
123 domain socket).
124 IN_DELETE (+)
126 File/directory deleted from watched directory.
127 IN_DELETE_SELF
129 Watched file/directory was itself deleted. (This event also
130 occurs if an object is moved to another filesystem, since
131 mv(1) in effect copies the file to the other filesystem and
132 then deletes it from the original filesystem.) In addition,
133 an IN_IGNORED event will subsequently be generated for the
134 watch descriptor.
135 IN_MODIFY (+)
137 File was modified (e.g., write(2), truncate(2)).
138 IN_MOVE_SELF
140 Watched file/directory was itself moved.
141 IN_MOVED_FROM (+)
143 Generated for the directory containing the old filename when
144 a file is renamed.
145 IN_MOVED_TO (+)
147 Generated for the directory containing the new filename when
148 a file is renamed.
149 IN_OPEN (*)
151 File or directory was opened.
152 Inotify monitoring is inode-based: when monitoring a file (but not when
154 monitoring the directory containing a file), an event can be generated
155 for activity on any link to the file (in the same or a different direc‐
156 tory).
157 When monitoring a directory:
159 * the events marked above with an asterisk (*) can occur both for the
161 directory itself and for objects inside the directory; and
162 * the events marked with a plus sign (+) occur only for objects inside
164 the directory (not for the directory itself).
165 Note: when monitoring a directory, events are not generated for the
167 files inside the directory when the events are performed via a pathname
168 (i.e., a link) that lies outside the monitored directory.
169 When events are generated for objects inside a watched directory, the
171 name field in the returned inotify_event structure identifies the name
172 of the file within the directory.
173 The IN_ALL_EVENTS macro is defined as a bit mask of all of the above
175 events. This macro can be used as the mask argument when calling ino‐
176 tify_add_watch(2).
177 Two additional convenience macros are defined:
179 IN_MOVE
181 Equates to IN_MOVED_FROM | IN_MOVED_TO.
182 IN_CLOSE
184 Equates to IN_CLOSE_WRITE | IN_CLOSE_NOWRITE.
185 The following further bits can be specified in mask when calling ino‐
187 tify_add_watch(2):
188 IN_DONT_FOLLOW (since Linux 2.6.15)
190 Don't dereference pathname if it is a symbolic link.
191 IN_EXCL_UNLINK (since Linux 2.6.36)
193 By default, when watching events on the children of a direc‐
194 tory, events are generated for children even after they have
195 been unlinked from the directory. This can result in large
196 numbers of uninteresting events for some applications (e.g.,
197 if watching /tmp, in which many applications create tempo‐
198 rary files whose names are immediately unlinked). Specify‐
199 ing IN_EXCL_UNLINK changes the default behavior, so that
200 events are not generated for children after they have been
201 unlinked from the watched directory.
202 IN_MASK_ADD
204 If a watch instance already exists for the filesystem object
205 corresponding to pathname, add (OR) the events in mask to
206 the watch mask (instead of replacing the mask); the error
207 EINVAL results if IN_MASK_CREATE is also specified.
208 IN_ONESHOT
210 Monitor the filesystem object corresponding to pathname for
211 one event, then remove from watch list.
212 IN_ONLYDIR (since Linux 2.6.15)
214 Watch pathname only if it is a directory; the error ENOTDIR
215 results if pathname is not a directory. Using this flag
216 provides an application with a race-free way of ensuring
217 that the monitored object is a directory.
218 IN_MASK_CREATE (since Linux 4.18)
220 Watch pathname only if it does not already have a watch as‐
221 sociated with it; the error EEXIST results if pathname is
222 already being watched.
223 Using this flag provides an application with a way of ensur‐
225 ing that new watches do not modify existing ones. This is
226 useful because multiple paths may refer to the same inode,
227 and multiple calls to inotify_add_watch(2) without this flag
228 may clobber existing watch masks.
229 The following bits may be set in the mask field returned by read(2):
231 IN_IGNORED
233 Watch was removed explicitly (inotify_rm_watch(2)) or auto‐
234 matically (file was deleted, or filesystem was unmounted).
235 See also BUGS.
236 IN_ISDIR
238 Subject of this event is a directory.
239 IN_Q_OVERFLOW
241 Event queue overflowed (wd is -1 for this event).
242 IN_UNMOUNT
244 Filesystem containing watched object was unmounted. In ad‐
245 dition, an IN_IGNORED event will subsequently be generated
246 for the watch descriptor.
247 Examples
249 Suppose an application is watching the directory dir and the file
250 dir/myfile for all events. The examples below show some events that
251 will be generated for these two objects.
252 fd = open("dir/myfile", O_RDWR);
254 Generates IN_OPEN events for both dir and dir/myfile.
255 read(fd, buf, count);
257 Generates IN_ACCESS events for both dir and dir/myfile.
258 write(fd, buf, count);
260 Generates IN_MODIFY events for both dir and dir/myfile.
261 fchmod(fd, mode);
263 Generates IN_ATTRIB events for both dir and dir/myfile.
264 close(fd);
266 Generates IN_CLOSE_WRITE events for both dir and dir/myfile.
267 Suppose an application is watching the directories dir1 and dir2, and
269 the file dir1/myfile. The following examples show some events that may
270 be generated.
271 link("dir1/myfile", "dir2/new");
273 Generates an IN_ATTRIB event for myfile and an IN_CREATE
274 event for dir2.
275 rename("dir1/myfile", "dir2/myfile");
277 Generates an IN_MOVED_FROM event for dir1, an IN_MOVED_TO
278 event for dir2, and an IN_MOVE_SELF event for myfile. The
279 IN_MOVED_FROM and IN_MOVED_TO events will have the same
280 cookie value.
281 Suppose that dir1/xx and dir2/yy are (the only) links to the same file,
283 and an application is watching dir1, dir2, dir1/xx, and dir2/yy. Exe‐
284 cuting the following calls in the order given below will generate the
285 following events:
286 unlink("dir2/yy");
288 Generates an IN_ATTRIB event for xx (because its link count
289 changes) and an IN_DELETE event for dir2.
290 unlink("dir1/xx");
292 Generates IN_ATTRIB, IN_DELETE_SELF, and IN_IGNORED events
293 for xx, and an IN_DELETE event for dir1.
294 Suppose an application is watching the directory dir and (the empty)
296 directory dir/subdir. The following examples show some events that may
297 be generated.
298 mkdir("dir/new", mode);
300 Generates an IN_CREATE | IN_ISDIR event for dir.
301 rmdir("dir/subdir");
303 Generates IN_DELETE_SELF and IN_IGNORED events for subdir,
304 and an IN_DELETE | IN_ISDIR event for dir.
305 /proc interfaces
307 The following interfaces can be used to limit the amount of kernel mem‐
308 ory consumed by inotify:
309 /proc/sys/fs/inotify/max_queued_events
311 The value in this file is used when an application calls ino‐
312 tify_init(2) to set an upper limit on the number of events that
313 can be queued to the corresponding inotify instance. Events in
314 excess of this limit are dropped, but an IN_Q_OVERFLOW event is
315 always generated.
316 /proc/sys/fs/inotify/max_user_instances
318 This specifies an upper limit on the number of inotify instances
319 that can be created per real user ID.
320 /proc/sys/fs/inotify/max_user_watches
322 This specifies an upper limit on the number of watches that can
323 be created per real user ID.
324
326 Inotify was merged into the 2.6.13 Linux kernel. The required library
327 interfaces were added to glibc in version 2.4. (IN_DONT_FOLLOW,
328 IN_MASK_ADD, and IN_ONLYDIR were added in glibc version 2.5.)
329
331 The inotify API is Linux-specific.
332
334 Inotify file descriptors can be monitored using select(2), poll(2), and
335 epoll(7). When an event is available, the file descriptor indicates as
336 readable.
337 Since Linux 2.6.25, signal-driven I/O notification is available for in‐
339 otify file descriptors; see the discussion of F_SETFL (for setting the
340 O_ASYNC flag), F_SETOWN, and F_SETSIG in fcntl(2). The siginfo_t
341 structure (described in sigaction(2)) that is passed to the signal han‐
342 dler has the following fields set: si_fd is set to the inotify file de‐
343 scriptor number; si_signo is set to the signal number; si_code is set
344 to POLL_IN; and POLLIN is set in si_band.
345 If successive output inotify events produced on the inotify file de‐
347 scriptor are identical (same wd, mask, cookie, and name), then they are
348 coalesced into a single event if the older event has not yet been read
349 (but see BUGS). This reduces the amount of kernel memory required for
350 the event queue, but also means that an application can't use inotify
351 to reliably count file events.
352 The events returned by reading from an inotify file descriptor form an
354 ordered queue. Thus, for example, it is guaranteed that when renaming
355 from one directory to another, events will be produced in the correct
356 order on the inotify file descriptor.
357 The set of watch descriptors that is being monitored via an inotify
359 file descriptor can be viewed via the entry for the inotify file de‐
360 scriptor in the process's /proc/[pid]/fdinfo directory. See proc(5)
361 for further details. The FIONREAD ioctl(2) returns the number of bytes
362 available to read from an inotify file descriptor.
363 Limitations and caveats
365 The inotify API provides no information about the user or process that
366 triggered the inotify event. In particular, there is no easy way for a
367 process that is monitoring events via inotify to distinguish events
368 that it triggers itself from those that are triggered by other pro‐
369 cesses.
370 Inotify reports only events that a user-space program triggers through
372 the filesystem API. As a result, it does not catch remote events that
373 occur on network filesystems. (Applications must fall back to polling
374 the filesystem to catch such events.) Furthermore, various pseudo-
375 filesystems such as /proc, /sys, and /dev/pts are not monitorable with
376 inotify.
377 The inotify API does not report file accesses and modifications that
379 may occur because of mmap(2), msync(2), and munmap(2).
380 The inotify API identifies affected files by filename. However, by the
382 time an application processes an inotify event, the filename may al‐
383 ready have been deleted or renamed.
384 The inotify API identifies events via watch descriptors. It is the ap‐
386 plication's responsibility to cache a mapping (if one is needed) be‐
387 tween watch descriptors and pathnames. Be aware that directory renam‐
388 ings may affect multiple cached pathnames.
389 Inotify monitoring of directories is not recursive: to monitor subdi‐
391 rectories under a directory, additional watches must be created. This
392 can take a significant amount time for large directory trees.
393 If monitoring an entire directory subtree, and a new subdirectory is
395 created in that tree or an existing directory is renamed into that
396 tree, be aware that by the time you create a watch for the new subdi‐
397 rectory, new files (and subdirectories) may already exist inside the
398 subdirectory. Therefore, you may want to scan the contents of the sub‐
399 directory immediately after adding the watch (and, if desired, recur‐
400 sively add watches for any subdirectories that it contains).
401 Note that the event queue can overflow. In this case, events are lost.
403 Robust applications should handle the possibility of lost events grace‐
404 fully. For example, it may be necessary to rebuild part or all of the
405 application cache. (One simple, but possibly expensive, approach is to
406 close the inotify file descriptor, empty the cache, create a new ino‐
407 tify file descriptor, and then re-create watches and cache entries for
408 the objects to be monitored.)
409 If a filesystem is mounted on top of a monitored directory, no event is
411 generated, and no events are generated for objects immediately under
412 the new mount point. If the filesystem is subsequently unmounted,
413 events will subsequently be generated for the directory and the objects
414 it contains.
415 Dealing with rename() events
417 As noted above, the IN_MOVED_FROM and IN_MOVED_TO event pair that is
418 generated by rename(2) can be matched up via their shared cookie value.
419 However, the task of matching has some challenges.
420 These two events are usually consecutive in the event stream available
422 when reading from the inotify file descriptor. However, this is not
423 guaranteed. If multiple processes are triggering events for monitored
424 objects, then (on rare occasions) an arbitrary number of other events
425 may appear between the IN_MOVED_FROM and IN_MOVED_TO events. Further‐
426 more, it is not guaranteed that the event pair is atomically inserted
427 into the queue: there may be a brief interval where the IN_MOVED_FROM
428 has appeared, but the IN_MOVED_TO has not.
429 Matching up the IN_MOVED_FROM and IN_MOVED_TO event pair generated by
431 rename(2) is thus inherently racy. (Don't forget that if an object is
432 renamed outside of a monitored directory, there may not even be an
433 IN_MOVED_TO event.) Heuristic approaches (e.g., assume the events are
434 always consecutive) can be used to ensure a match in most cases, but
435 will inevitably miss some cases, causing the application to perceive
436 the IN_MOVED_FROM and IN_MOVED_TO events as being unrelated. If watch
437 descriptors are destroyed and re-created as a result, then those watch
438 descriptors will be inconsistent with the watch descriptors in any
439 pending events. (Re-creating the inotify file descriptor and rebuild‐
440 ing the cache may be useful to deal with this scenario.)
441 Applications should also allow for the possibility that the
443 IN_MOVED_FROM event was the last event that could fit in the buffer re‐
444 turned by the current call to read(2), and the accompanying IN_MOVED_TO
445 event might be fetched only on the next read(2), which should be done
446 with a (small) timeout to allow for the fact that insertion of the
447 IN_MOVED_FROM-IN_MOVED_TO event pair is not atomic, and also the possi‐
448 bility that there may not be any IN_MOVED_TO event.
449
451 Before Linux 3.19, fallocate(2) did not create any inotify events.
452 Since Linux 3.19, calls to fallocate(2) generate IN_MODIFY events.
453 In kernels before 2.6.16, the IN_ONESHOT mask flag does not work.
455 As originally designed and implemented, the IN_ONESHOT flag did not
457 cause an IN_IGNORED event to be generated when the watch was dropped
458 after one event. However, as an unintended effect of other changes,
459 since Linux 2.6.36, an IN_IGNORED event is generated in this case.
460 Before kernel 2.6.25, the kernel code that was intended to coalesce
462 successive identical events (i.e., the two most recent events could po‐
463 tentially be coalesced if the older had not yet been read) instead
464 checked if the most recent event could be coalesced with the oldest un‐
465 read event.
466 When a watch descriptor is removed by calling inotify_rm_watch(2) (or
468 because a watch file is deleted or the filesystem that contains it is
469 unmounted), any pending unread events for that watch descriptor remain
470 available to read. As watch descriptors are subsequently allocated
471 with inotify_add_watch(2), the kernel cycles through the range of pos‐
472 sible watch descriptors (0 to INT_MAX) incrementally. When allocating
473 a free watch descriptor, no check is made to see whether that watch de‐
474 scriptor number has any pending unread events in the inotify queue.
475 Thus, it can happen that a watch descriptor is reallocated even when
476 pending unread events exist for a previous incarnation of that watch
477 descriptor number, with the result that the application might then read
478 those events and interpret them as belonging to the file associated
479 with the newly recycled watch descriptor. In practice, the likelihood
480 of hitting this bug may be extremely low, since it requires that an ap‐
481 plication cycle through INT_MAX watch descriptors, release a watch de‐
482 scriptor while leaving unread events for that watch descriptor in the
483 queue, and then recycle that watch descriptor. For this reason, and
484 because there have been no reports of the bug occurring in real-world
485 applications, as of Linux 3.15, no kernel changes have yet been made to
486 eliminate this possible bug.
487
489 The following program demonstrates the usage of the inotify API. It
490 marks the directories passed as a command-line arguments and waits for
491 events of type IN_OPEN, IN_CLOSE_NOWRITE, and IN_CLOSE_WRITE.
492 The following output was recorded while editing the file
494 /home/user/temp/foo and listing directory /tmp. Before the file and
495 the directory were opened, IN_OPEN events occurred. After the file was
496 closed, an IN_CLOSE_WRITE event occurred. After the directory was
497 closed, an IN_CLOSE_NOWRITE event occurred. Execution of the program
498 ended when the user pressed the ENTER key.
499 Example output
501 $ ./a.out /tmp /home/user/temp
502 Press enter key to terminate.
503 Listening for events.
504 IN_OPEN: /home/user/temp/foo [file]
505 IN_CLOSE_WRITE: /home/user/temp/foo [file]
506 IN_OPEN: /tmp/ [directory]
507 IN_CLOSE_NOWRITE: /tmp/ [directory]
508 Listening for events stopped.
510 Program source
512 #include <errno.h>
514 #include <poll.h>
515 #include <stdio.h>
516 #include <stdlib.h>
517 #include <sys/inotify.h>
518 #include <unistd.h>
519 #include <string.h>
520 /* Read all available inotify events from the file descriptor 'fd'.
522 wd is the table of watch descriptors for the directories in argv.
523 argc is the length of wd and argv.
524 argv is the list of watched directories.
525 Entry 0 of wd and argv is unused. */
526 static void
528 handle_events(int fd, int *wd, int argc, char* argv[])
529 {
530 /* Some systems cannot read integer variables if they are not
531 properly aligned. On other systems, incorrect alignment may
532 decrease performance. Hence, the buffer used for reading from
533 the inotify file descriptor should have the same alignment as
534 struct inotify_event. */
535 char buf[4096]
537 __attribute__ ((aligned(__alignof__(struct inotify_event))));
538 const struct inotify_event *event;
539 ssize_t len;
540 /* Loop while events can be read from inotify file descriptor. */
542 for (;;) {
544 /* Read some events. */
546 len = read(fd, buf, sizeof(buf));
548 if (len == -1 && errno != EAGAIN) {
549 perror("read");
550 exit(EXIT_FAILURE);
551 }
552 /* If the nonblocking read() found no events to read, then
554 it returns -1 with errno set to EAGAIN. In that case,
555 we exit the loop. */
556 if (len <= 0)
558 break;
559 /* Loop over all events in the buffer */
561 for (char *ptr = buf; ptr < buf + len;
563 ptr += sizeof(struct inotify_event) + event->len) {
564 event = (const struct inotify_event *) ptr;
566 /* Print event type */
568 if (event->mask & IN_OPEN)
570 printf("IN_OPEN: ");
571 if (event->mask & IN_CLOSE_NOWRITE)
572 printf("IN_CLOSE_NOWRITE: ");
573 if (event->mask & IN_CLOSE_WRITE)
574 printf("IN_CLOSE_WRITE: ");
575 /* Print the name of the watched directory */
577 for (int i = 1; i < argc; ++i) {
579 if (wd[i] == event->wd) {
580 printf("%s/", argv[i]);
581 break;
582 }
583 }
584 /* Print the name of the file */
586 if (event->len)
588 printf("%s", event->name);
589 /* Print type of filesystem object */
591 if (event->mask & IN_ISDIR)
593 printf(" [directory]\n");
594 else
595 printf(" [file]\n");
596 }
597 }
598 }
599 int
601 main(int argc, char* argv[])
602 {
603 char buf;
604 int fd, i, poll_num;
605 int *wd;
606 nfds_t nfds;
607 struct pollfd fds[2];
608 if (argc < 2) {
610 printf("Usage: %s PATH [PATH ...]\n", argv[0]);
611 exit(EXIT_FAILURE);
612 }
613 printf("Press ENTER key to terminate.\n");
615 /* Create the file descriptor for accessing the inotify API */
617 fd = inotify_init1(IN_NONBLOCK);
619 if (fd == -1) {
620 perror("inotify_init1");
621 exit(EXIT_FAILURE);
622 }
623 /* Allocate memory for watch descriptors */
625 wd = calloc(argc, sizeof(int));
627 if (wd == NULL) {
628 perror("calloc");
629 exit(EXIT_FAILURE);
630 }
631 /* Mark directories for events
633 - file was opened
634 - file was closed */
635 for (i = 1; i < argc; i++) {
637 wd[i] = inotify_add_watch(fd, argv[i],
638 IN_OPEN | IN_CLOSE);
639 if (wd[i] == -1) {
640 fprintf(stderr, "Cannot watch '%s': %s\n",
641 argv[i], strerror(errno));
642 exit(EXIT_FAILURE);
643 }
644 }
645 /* Prepare for polling */
647 nfds = 2;
649 /* Console input */
651 fds[0].fd = STDIN_FILENO;
653 fds[0].events = POLLIN;
654 /* Inotify input */
656 fds[1].fd = fd;
658 fds[1].events = POLLIN;
659 /* Wait for events and/or terminal input */
661 printf("Listening for events.\n");
663 while (1) {
664 poll_num = poll(fds, nfds, -1);
665 if (poll_num == -1) {
666 if (errno == EINTR)
667 continue;
668 perror("poll");
669 exit(EXIT_FAILURE);
670 }
671 if (poll_num > 0) {
673 if (fds[0].revents & POLLIN) {
675 /* Console input is available. Empty stdin and quit */
677 while (read(STDIN_FILENO, &buf, 1) > 0 && buf != '\n')
679 continue;
680 break;
681 }
682 if (fds[1].revents & POLLIN) {
684 /* Inotify events are available */
686 handle_events(fd, wd, argc, argv);
688 }
689 }
690 }
691 printf("Listening for events stopped.\n");
693 /* Close inotify file descriptor */
695 close(fd);
697 free(wd);
699 exit(EXIT_SUCCESS);
700 }
701
703 inotifywait(1), inotifywatch(1), inotify_add_watch(2), inotify_init(2),
704 inotify_init1(2), inotify_rm_watch(2), read(2), stat(2), fanotify(7)
705 Documentation/filesystems/inotify.txt in the Linux kernel source tree
707
709 This page is part of release 5.10 of the Linux man-pages project. A
710 description of the project, information about reporting bugs, and the
711 latest version of this page, can be found at
712 https://www.kernel.org/doc/man-pages/.
713Linux 2020-11-01 INOTIFY(7)