INOTIFY(7)                (2020-11-01)                 INOTIFY(7)

     NAME
          inotify - monitoring filesystem events

     DESCRIPTION
          The inotify API provides a mechanism for monitoring filesys-
          tem events.  Inotify can be used to monitor individual
          files, or to monitor directories.  When a directory is moni-
          tored, inotify will return events for the directory itself,
          and for files inside the directory.

          The following system calls are used with this API:

          *  inotify_init(2) creates an inotify instance and returns a
             file descriptor referring to the inotify instance.  The
             more recent inotify_init1(2) is like inotify_init(2), but
             has a flags argument that provides access to some extra
             functionality.

          *  inotify_add_watch(2) manipulates the "watch list" associ-
             ated with an inotify instance.  Each item ("watch") in
             the watch list specifies the pathname of a file or direc-
             tory, along with some set of events that the kernel
             should monitor for the file referred to by that pathname.
             inotify_add_watch(2) either creates a new watch item, or
             modifies an existing watch.  Each watch has a unique
             "watch descriptor", an integer returned by
             inotify_add_watch(2) when the watch is created.

          *  When events occur for monitored files and directories,
             those events are made available to the application as
             structured data that can be read from the inotify file
             descriptor using read(2) (see below).

          *  inotify_rm_watch(2) removes an item from an inotify watch
             list.

          *  When all file descriptors referring to an inotify
             instance have been closed (using close(2)), the underly-
             ing object and its resources are freed for reuse by the
             kernel; all associated watches are automatically freed.

          With careful programming, an application can use inotify to
          efficiently monitor and cache the state of a set of filesys-
          tem objects.  However, robust applications should allow for
          the fact that bugs in the monitoring logic or races of the
          kind described below may leave the cache inconsistent with
          the filesystem state.  It is probably wise to do some con-
          sistency checking, and rebuild the cache when inconsisten-
          cies are detected.

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        Reading events from an inotify file
          To determine what events have occurred, an application
          read(2)s from the inotify file descriptor.  If no events
          have so far occurred, then, assuming a blocking file
          descriptor, read(2) will block until at least one event
          occurs (unless interrupted by a signal, in which case the
          call fails with the error EINTR; see signal(7)).

          Each successful read(2) returns a buffer containing one or
          more of the following structures:

              struct inotify_event {
                  int      wd;       /* Watch descriptor */
                  uint32_t mask;     /* Mask describing event */
                  uint32_t cookie;   /* Unique cookie associating related
                                        events (for rename(2)) */
                  uint32_t len;      /* Size of name field */
                  char     name[];   /* Optional null-terminated name */
              };

          wd identifies the watch for which this event occurs.  It is
          one of the watch descriptors returned by a previous call to
          inotify_add_watch(2).

          mask contains bits that describe the event that occurred
          (see below).

          cookie is a unique integer that connects related events.
          Currently, this is used only for rename events, and allows
          the resulting pair of IN_MOVED_FROM and IN_MOVED_TO events
          to be connected by the application.  For all other event
          types, cookie is set to 0.

          The name field is present only when an event is returned for
          a file inside a watched directory; it identifies the file-
          name within the watched directory.  This filename is null-
          terminated, and may include further null bytes (aq\0aq) to
          align subsequent reads to a suitable address boundary.

          The len field counts all of the bytes in name, including the
          null bytes; the length of each inotify_event structure is
          thus sizeof(struct inotify_event)+len.

          The behavior when the buffer given to read(2) is too small
          to return information about the next event depends on the
          kernel version: in kernels before 2.6.21, read(2) returns 0;
          since kernel 2.6.21, read(2) fails with the error EINVAL.
          Specifying a buffer of size

              sizeof(struct inotify_event) + NAME_MAX + 1

          will be sufficient to read at least one event.

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        inotify events
          The inotify_add_watch(2) mask argument and the mask field of
          the inotify_event structure returned when read(2)ing an ino-
          tify file descriptor are both bit masks identifying inotify
          events.  The following bits can be specified in mask when
          calling inotify_add_watch(2) and may be returned in the mask
          field returned by read(2):

              IN_ACCESS (+)
                   File was accessed (e.g., read(2), execve(2)).

              IN_ATTRIB (*)
                   Metadata changed-for example, permissions (e.g.,
                   chmod(2)), timestamps (e.g., utimensat(2)),
                   extended attributes (setxattr(2)), link count
                   (since Linux 2.6.25; e.g., for the target of
                   link(2) and for unlink(2)), and user/group ID
                   (e.g., chown(2)).

              IN_CLOSE_WRITE (+)
                   File opened for writing was closed.

              IN_CLOSE_NOWRITE (*)
                   File or directory not opened for writing was
                   closed.

              IN_CREATE (+)
                   File/directory created in watched directory (e.g.,
                   open(2) O_CREAT, mkdir(2), link(2), symlink(2),
                   bind(2) on a UNIX domain socket).

              IN_DELETE (+)
                   File/directory deleted from watched directory.

              IN_DELETE_SELF
                   Watched file/directory was itself deleted.  (This
                   event also occurs if an object is moved to another
                   filesystem, since mv(1) in effect copies the file
                   to the other filesystem and then deletes it from
                   the original filesystem.)  In addition, an
                   IN_IGNORED event will subsequently be generated for
                   the watch descriptor.

              IN_MODIFY (+)
                   File was modified (e.g., write(2), truncate(2)).

              IN_MOVE_SELF
                   Watched file/directory was itself moved.

              IN_MOVED_FROM (+)
                   Generated for the directory containing the old
                   filename when a file is renamed.

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              IN_MOVED_TO (+)
                   Generated for the directory containing the new
                   filename when a file is renamed.

              IN_OPEN (*)
                   File or directory was opened.

          Inotify monitoring is inode-based: when monitoring a file
          (but not when monitoring the directory containing a file),
          an event can be generated for activity on any link to the
          file (in the same or a different directory).

          When monitoring a directory:

          *  the events marked above with an asterisk (*) can occur
             both for the directory itself and for objects inside the
             directory; and

          *  the events marked with a plus sign (+) occur only for
             objects inside the directory (not for the directory
             itself).

          Note: when monitoring a directory, events are not generated
          for the files inside the directory when the events are per-
          formed via a pathname (i.e., a link) that lies outside the
          monitored directory.

          When events are generated for objects inside a watched
          directory, the name field in the returned inotify_event
          structure identifies the name of the file within the direc-
          tory.

          The IN_ALL_EVENTS macro is defined as a bit mask of all of
          the above events.  This macro can be used as the mask argu-
          ment when calling inotify_add_watch(2).

          Two additional convenience macros are defined:

              IN_MOVE
                   Equates to IN_MOVED_FROM | IN_MOVED_TO.

              IN_CLOSE
                   Equates to IN_CLOSE_WRITE | IN_CLOSE_NOWRITE.

          The following further bits can be specified in mask when
          calling inotify_add_watch(2):

              IN_DONT_FOLLOW (since Linux 2.6.15)
                   Don't dereference pathname if it is a symbolic
                   link.

              IN_EXCL_UNLINK (since Linux 2.6.36)

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                   By default, when watching events on the children of
                   a directory, events are generated for children even
                   after they have been unlinked from the directory.
                   This can result in large numbers of uninteresting
                   events for some applications (e.g., if watching
                   /tmp, in which many applications create temporary
                   files whose names are immediately unlinked).  Spec-
                   ifying IN_EXCL_UNLINK changes the default behavior,
                   so that events are not generated for children after
                   they have been unlinked from the watched directory.

              IN_MASK_ADD
                   If a watch instance already exists for the filesys-
                   tem object corresponding to pathname, add (OR) the
                   events in mask to the watch mask (instead of
                   replacing the mask); the error EINVAL results if
                   IN_MASK_CREATE is also specified.

              IN_ONESHOT
                   Monitor the filesystem object corresponding to
                   pathname for one event, then remove from watch
                   list.

              IN_ONLYDIR (since Linux 2.6.15)
                   Watch pathname only if it is a directory; the error
                   ENOTDIR results if pathname is not a directory.
                   Using this flag provides an application with a
                   race-free way of ensuring that the monitored object
                   is a directory.

              IN_MASK_CREATE (since Linux 4.18)
                   Watch pathname only if it does not already have a
                   watch associated with it; the error EEXIST results
                   if pathname is already being watched.

                   Using this flag provides an application with a way
                   of ensuring that new watches do not modify existing
                   ones.  This is useful because multiple paths may
                   refer to the same inode, and multiple calls to
                   inotify_add_watch(2) without this flag may clobber
                   existing watch masks.

          The following bits may be set in the mask field returned by
          read(2):

              IN_IGNORED
                   Watch was removed explicitly (inotify_rm_watch(2))
                   or automatically (file was deleted, or filesystem
                   was unmounted).  See also BUGS.

              IN_ISDIR
                   Subject of this event is a directory.

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              IN_Q_OVERFLOW
                   Event queue overflowed (wd is -1 for this event).

              IN_UNMOUNT
                   Filesystem containing watched object was unmounted.
                   In addition, an IN_IGNORED event will subsequently
                   be generated for the watch descriptor.

        Examples
          Suppose an application is watching the directory dir and the
          file dir/myfile for all events.  The examples below show
          some events that will be generated for these two objects.

              fd = open("dir/myfile", O_RDWR);
                   Generates IN_OPEN events for both dir and
                   dir/myfile.

              read(fd, buf, count);
                   Generates IN_ACCESS events for both dir and
                   dir/myfile.

              write(fd, buf, count);
                   Generates IN_MODIFY events for both dir and
                   dir/myfile.

              fchmod(fd, mode);
                   Generates IN_ATTRIB events for both dir and
                   dir/myfile.

              close(fd);
                   Generates IN_CLOSE_WRITE events for both dir and
                   dir/myfile.

          Suppose an application is watching the directories dir1 and
          dir2, and the file dir1/myfile. The following examples show
          some events that may be generated.

              link("dir1/myfile", "dir2/new");
                   Generates an IN_ATTRIB event for myfile and an
                   IN_CREATE event for dir2.

              rename("dir1/myfile", "dir2/myfile");
                   Generates an IN_MOVED_FROM event for dir1, an
                   IN_MOVED_TO event for dir2, and an IN_MOVE_SELF
                   event for myfile. The IN_MOVED_FROM and IN_MOVED_TO
                   events will have the same cookie value.

          Suppose that dir1/xx and dir2/yy are (the only) links to the
          same file, and an application is watching dir1, dir2,
          dir1/xx, and dir2/yy. Executing the following calls in the
          order given below will generate the following events:

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              unlink("dir2/yy");
                   Generates an IN_ATTRIB event for xx (because its
                   link count changes) and an IN_DELETE event for
                   dir2.

              unlink("dir1/xx");
                   Generates IN_ATTRIB, IN_DELETE_SELF, and IN_IGNORED
                   events for xx, and an IN_DELETE event for dir1.

          Suppose an application is watching the directory dir and
          (the empty) directory dir/subdir. The following examples
          show some events that may be generated.

              mkdir("dir/new", mode);
                   Generates an IN_CREATE | IN_ISDIR event for dir.

              rmdir("dir/subdir");
                   Generates IN_DELETE_SELF and IN_IGNORED events for
                   subdir, and an IN_DELETE | IN_ISDIR event for dir.

        /proc interfaces
          The following interfaces can be used to limit the amount of
          kernel memory consumed by inotify:

          /proc/sys/fs/inotify/max_queued_events
               The value in this file is used when an application
               calls inotify_init(2) to set an upper limit on the num-
               ber of events that can be queued to the corresponding
               inotify instance.  Events in excess of this limit are
               dropped, but an IN_Q_OVERFLOW event is always gener-
               ated.

          /proc/sys/fs/inotify/max_user_instances
               This specifies an upper limit on the number of inotify
               instances that can be created per real user ID.

          /proc/sys/fs/inotify/max_user_watches
               This specifies an upper limit on the number of watches
               that can be created per real user ID.

     VERSIONS
          Inotify was merged into the 2.6.13 Linux kernel.  The
          required library interfaces were added to glibc in version
          2.4.  (IN_DONT_FOLLOW, IN_MASK_ADD, and IN_ONLYDIR were
          added in glibc version 2.5.)

     CONFORMING TO
          The inotify API is Linux-specific.

     NOTES
          Inotify file descriptors can be monitored using select(2),
          poll(2), and epoll(7).  When an event is available, the file

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          descriptor indicates as readable.

          Since Linux 2.6.25, signal-driven I/O notification is avail-
          able for inotify file descriptors; see the discussion of
          F_SETFL (for setting the O_ASYNC flag), F_SETOWN, and
          F_SETSIG in fcntl(2).  The siginfo_t structure (described in
          sigaction(2)) that is passed to the signal handler has the
          following fields set: si_fd is set to the inotify file
          descriptor number; si_signo is set to the signal number;
          si_code is set to POLL_IN; and POLLIN is set in si_band.

          If successive output inotify events produced on the inotify
          file descriptor are identical (same wd, mask, cookie, and
          name), then they are coalesced into a single event if the
          older event has not yet been read (but see BUGS).  This
          reduces the amount of kernel memory required for the event
          queue, but also means that an application can't use inotify
          to reliably count file events.

          The events returned by reading from an inotify file descrip-
          tor form an ordered queue.  Thus, for example, it is guaran-
          teed that when renaming from one directory to another,
          events will be produced in the correct order on the inotify
          file descriptor.

          The set of watch descriptors that is being monitored via an
          inotify file descriptor can be viewed via the entry for the
          inotify file descriptor in the process's /proc/[pid]/fdinfo
          directory.  See proc(5) for further details.  The FIONREAD
          ioctl(2) returns the number of bytes available to read from
          an inotify file descriptor.

        Limitations and caveats
          The inotify API provides no information about the user or
          process that triggered the inotify event.  In particular,
          there is no easy way for a process that is monitoring events
          via inotify to distinguish events that it triggers itself
          from those that are triggered by other processes.

          Inotify reports only events that a user-space program trig-
          gers through the filesystem API.  As a result, it does not
          catch remote events that occur on network filesystems.
          (Applications must fall back to polling the filesystem to
          catch such events.)  Furthermore, various pseudo-filesystems
          such as /proc, /sys, and /dev/pts are not monitorable with
          inotify.

          The inotify API does not report file accesses and modifica-
          tions that may occur because of mmap(2), msync(2), and
          munmap(2).

          The inotify API identifies affected files by filename.

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          However, by the time an application processes an inotify
          event, the filename may already have been deleted or
          renamed.

          The inotify API identifies events via watch descriptors.  It
          is the application's responsibility to cache a mapping (if
          one is needed) between watch descriptors and pathnames.  Be
          aware that directory renamings may affect multiple cached
          pathnames.

          Inotify monitoring of directories is not recursive: to moni-
          tor subdirectories under a directory, additional watches
          must be created.  This can take a significant amount time
          for large directory trees.

          If monitoring an entire directory subtree, and a new subdi-
          rectory is created in that tree or an existing directory is
          renamed into that tree, be aware that by the time you create
          a watch for the new subdirectory, new files (and subdirecto-
          ries) may already exist inside the subdirectory.  Therefore,
          you may want to scan the contents of the subdirectory imme-
          diately after adding the watch (and, if desired, recursively
          add watches for any subdirectories that it contains).

          Note that the event queue can overflow.  In this case,
          events are lost.  Robust applications should handle the pos-
          sibility of lost events gracefully.  For example, it may be
          necessary to rebuild part or all of the application cache.
          (One simple, but possibly expensive, approach is to close
          the inotify file descriptor, empty the cache, create a new
          inotify file descriptor, and then re-create watches and
          cache entries for the objects to be monitored.)

          If a filesystem is mounted on top of a monitored directory,
          no event is generated, and no events are generated for
          objects immediately under the new mount point.  If the
          filesystem is subsequently unmounted, events will subse-
          quently be generated for the directory and the objects it
          contains.

        Dealing with rename() events
          As noted above, the IN_MOVED_FROM and IN_MOVED_TO event pair
          that is generated by rename(2) can be matched up via their
          shared cookie value.  However, the task of matching has some
          challenges.

          These two events are usually consecutive in the event stream
          available when reading from the inotify file descriptor.
          However, this is not guaranteed.  If multiple processes are
          triggering events for monitored objects, then (on rare occa-
          sions) an arbitrary number of other events may appear
          between the IN_MOVED_FROM and IN_MOVED_TO events.

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          Furthermore, it is not guaranteed that the event pair is
          atomically inserted into the queue: there may be a brief
          interval where the IN_MOVED_FROM has appeared, but the
          IN_MOVED_TO has not.

          Matching up the IN_MOVED_FROM and IN_MOVED_TO event pair
          generated by rename(2) is thus inherently racy.  (Don't for-
          get that if an object is renamed outside of a monitored
          directory, there may not even be an IN_MOVED_TO event.)
          Heuristic approaches (e.g., assume the events are always
          consecutive) can be used to ensure a match in most cases,
          but will inevitably miss some cases, causing the application
          to perceive the IN_MOVED_FROM and IN_MOVED_TO events as
          being unrelated.  If watch descriptors are destroyed and
          re-created as a result, then those watch descriptors will be
          inconsistent with the watch descriptors in any pending
          events.  (Re-creating the inotify file descriptor and
          rebuilding the cache may be useful to deal with this sce-
          nario.)

          Applications should also allow for the possibility that the
          IN_MOVED_FROM event was the last event that could fit in the
          buffer returned by the current call to read(2), and the
          accompanying IN_MOVED_TO event might be fetched only on the
          next read(2), which should be done with a (small) timeout to
          allow for the fact that insertion of the
          IN_MOVED_FROM-IN_MOVED_TO event pair is not atomic, and also
          the possibility that there may not be any IN_MOVED_TO event.

     BUGS
          Before Linux 3.19, fallocate(2) did not create any inotify
          events.  Since Linux 3.19, calls to fallocate(2) generate
          IN_MODIFY events.

          In kernels before 2.6.16, the IN_ONESHOT mask flag does not
          work.

          As originally designed and implemented, the IN_ONESHOT flag
          did not cause an IN_IGNORED event to be generated when the
          watch was dropped after one event.  However, as an unin-
          tended effect of other changes, since Linux 2.6.36, an
          IN_IGNORED event is generated in this case.

          Before kernel 2.6.25, the kernel code that was intended to
          coalesce successive identical events (i.e., the two most
          recent events could potentially be coalesced if the older
          had not yet been read) instead checked if the most recent
          event could be coalesced with the oldest unread event.

          When a watch descriptor is removed by calling
          inotify_rm_watch(2) (or because a watch file is deleted or
          the filesystem that contains it is unmounted), any pending

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          unread events for that watch descriptor remain available to
          read.  As watch descriptors are subsequently allocated with
          inotify_add_watch(2), the kernel cycles through the range of
          possible watch descriptors (0 to INT_MAX) incrementally.
          When allocating a free watch descriptor, no check is made to
          see whether that watch descriptor number has any pending
          unread events in the inotify queue.  Thus, it can happen
          that a watch descriptor is reallocated even when pending
          unread events exist for a previous incarnation of that watch
          descriptor number, with the result that the application
          might then read those events and interpret them as belonging
          to the file associated with the newly recycled watch
          descriptor.  In practice, the likelihood of hitting this bug
          may be extremely low, since it requires that an application
          cycle through INT_MAX watch descriptors, release a watch
          descriptor while leaving unread events for that watch
          descriptor in the queue, and then recycle that watch
          descriptor.  For this reason, and because there have been no
          reports of the bug occurring in real-world applications, as
          of Linux 3.15, no kernel changes have yet been made to elim-
          inate this possible bug.

     EXAMPLES
          The following program demonstrates the usage of the inotify
          API.  It marks the directories passed as a command-line
          arguments and waits for events of type IN_OPEN,
          IN_CLOSE_NOWRITE, and IN_CLOSE_WRITE.

          The following output was recorded while editing the file
          /home/user/temp/foo and listing directory /tmp. Before the
          file and the directory were opened, IN_OPEN events occurred.
          After the file was closed, an IN_CLOSE_WRITE event occurred.
          After the directory was closed, an IN_CLOSE_NOWRITE event
          occurred.  Execution of the program ended when the user
          pressed the ENTER key.

        Example output
              $ ./a.out /tmp /home/user/temp
              Press enter key to terminate.
              Listening for events.
              IN_OPEN: /home/user/temp/foo [file]
              IN_CLOSE_WRITE: /home/user/temp/foo [file]
              IN_OPEN: /tmp/ [directory]
              IN_CLOSE_NOWRITE: /tmp/ [directory]

              Listening for events stopped.

        Program source

          #include <errno.h>
          #include <poll.h>
          #include <stdio.h>

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          #include <stdlib.h>
          #include <sys/inotify.h>
          #include <unistd.h>
          #include <string.h>

          /* Read all available inotify events from the file descriptor aqfdaq.
             wd is the table of watch descriptors for the directories in argv.
             argc is the length of wd and argv.
             argv is the list of watched directories.
             Entry 0 of wd and argv is unused. */

          static void
          handle_events(int fd, int *wd, int argc, char* argv[])
          {
              /* Some systems cannot read integer variables if they are not
                 properly aligned. On other systems, incorrect alignment may
                 decrease performance. Hence, the buffer used for reading from
                 the inotify file descriptor should have the same alignment as
                 struct inotify_event. */

              char buf[4096]
                  __attribute__ ((aligned(__alignof__(struct inotify_event))));
              const struct inotify_event *event;
              ssize_t len;

              /* Loop while events can be read from inotify file descriptor. */

              for (;;) {

                  /* Read some events. */

                  len = read(fd, buf, sizeof(buf));
                  if (len == -1 && errno != EAGAIN) {
                      perror("read");
                      exit(EXIT_FAILURE);
                  }

                  /* If the nonblocking read() found no events to read, then
                     it returns -1 with errno set to EAGAIN. In that case,
                     we exit the loop. */

                  if (len <= 0)
                      break;

                  /* Loop over all events in the buffer */

                  for (char *ptr = buf; ptr < buf + len;
                          ptr += sizeof(struct inotify_event) + event->len) {

                      event = (const struct inotify_event *) ptr;

                      /* Print event type */

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                      if (event->mask & IN_OPEN)
                          printf("IN_OPEN: ");
                      if (event->mask & IN_CLOSE_NOWRITE)
                          printf("IN_CLOSE_NOWRITE: ");
                      if (event->mask & IN_CLOSE_WRITE)
                          printf("IN_CLOSE_WRITE: ");

                      /* Print the name of the watched directory */

                      for (int i = 1; i < argc; ++i) {
                          if (wd[i] == event->wd) {
                              printf("%s/", argv[i]);
                              break;
                          }
                      }

                      /* Print the name of the file */

                      if (event->len)
                          printf("%s", event->name);

                      /* Print type of filesystem object */

                      if (event->mask & IN_ISDIR)
                          printf(" [directory]\n");
                      else
                          printf(" [file]\n");
                  }
              }
          }

          int
          main(int argc, char* argv[])
          {
              char buf;
              int fd, i, poll_num;
              int *wd;
              nfds_t nfds;
              struct pollfd fds[2];

              if (argc < 2) {
                  printf("Usage: %s PATH [PATH ...]\n", argv[0]);
                  exit(EXIT_FAILURE);
              }

              printf("Press ENTER key to terminate.\n");

              /* Create the file descriptor for accessing the inotify API */

              fd = inotify_init1(IN_NONBLOCK);
              if (fd == -1) {
                  perror("inotify_init1");

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                  exit(EXIT_FAILURE);
              }

              /* Allocate memory for watch descriptors */

              wd = calloc(argc, sizeof(int));
              if (wd == NULL) {
                  perror("calloc");
                  exit(EXIT_FAILURE);
              }

              /* Mark directories for events
                 - file was opened
                 - file was closed */

              for (i = 1; i < argc; i++) {
                  wd[i] = inotify_add_watch(fd, argv[i],
                                            IN_OPEN | IN_CLOSE);
                  if (wd[i] == -1) {
                      fprintf(stderr, "Cannot watch aq%saq: %s\n",
                              argv[i], strerror(errno));
                      exit(EXIT_FAILURE);
                  }
              }

              /* Prepare for polling */

              nfds = 2;

              /* Console input */

              fds[0].fd = STDIN_FILENO;
              fds[0].events = POLLIN;

              /* Inotify input */

              fds[1].fd = fd;
              fds[1].events = POLLIN;

              /* Wait for events and/or terminal input */

              printf("Listening for events.\n");
              while (1) {
                  poll_num = poll(fds, nfds, -1);
                  if (poll_num == -1) {
                      if (errno == EINTR)
                          continue;
                      perror("poll");
                      exit(EXIT_FAILURE);
                  }

                  if (poll_num > 0) {

     Page 14                       Linux             (printed 5/24/22)

     INOTIFY(7)                (2020-11-01)                 INOTIFY(7)

                      if (fds[0].revents & POLLIN) {

                          /* Console input is available. Empty stdin and quit */

                          while (read(STDIN_FILENO, &buf, 1) > 0 && buf != aq\naq)
                              continue;
                          break;
                      }

                      if (fds[1].revents & POLLIN) {

                          /* Inotify events are available */

                          handle_events(fd, wd, argc, argv);
                      }
                  }
              }

              printf("Listening for events stopped.\n");

              /* Close inotify file descriptor */

              close(fd);

              free(wd);
              exit(EXIT_SUCCESS);
          }

     SEE ALSO
          inotifywait(1), inotifywatch(1), inotify_add_watch(2),
          inotify_init(2), inotify_init1(2), inotify_rm_watch(2),
          read(2), stat(2), fanotify(7)

          Documentation/filesystems/inotify.txt in the Linux kernel
          source tree

     COLOPHON
          This page is part of release 5.10 of the Linux man-pages
          project.  A description of the project, information about
          reporting bugs, and the latest version of this page, can be
          found at https://www.kernel.org/doc/man-pages/.

     Page 15                       Linux             (printed 5/24/22)