INOTIFY_ADD_WATCH(2)       Linux Programmer's Manual      INOTIFY_ADD_WATCH(2)

       inotify_add_watch - add a watch to an initialized inotify instance

       #include <sys/inotify.h>

       int inotify_add_watch(int fd, const char *pathname, uint32_t mask);

       inotify_add_watch()  adds  a  new watch, or modifies an existing watch,
       for the file whose location is specified in pathname; the  caller  must
       have read permission for this file.  The fd argument is a file descrip-
       tor referring to the inotify instance whose watch list is to  be  modi-
       fied.   The  events  to  be monitored for pathname are specified in the
       mask bit-mask argument.  See inotify(7) for a description of  the  bits
       that can be set in mask.

       A  successful  call  to  inotify_add_watch() returns a unique watch de-
       scriptor for this inotify instance, for the filesystem  object  (inode)
       that  corresponds to pathname.  If the filesystem object was not previ-
       ously being watched by this inotify instance, then the watch descriptor
       is newly allocated.  If the filesystem object was already being watched
       (perhaps via a different link to the same object), then the  descriptor
       for the existing watch is returned.

       The  watch  descriptor  is  returned by later read(2)s from the inotify
       file descriptor.  These reads fetch inotify_event structures (see  ino-
       tify(7)) indicating filesystem events; the watch descriptor inside this
       structure identifies the object for which the event occurred.

       On success, inotify_add_watch() returns a watch descriptor (a  nonnega-
       tive  integer).   On  error,  -1 is returned and errno is set appropri-

       EACCES Read access to the given file is not permitted.

       EBADF  The given file descriptor is not valid.

       EEXIST mask contains IN_MASK_CREATE and pathname refers to a  file  al-
              ready being watched by the same fd.

       EFAULT pathname  points  outside  of  the  process's accessible address

       EINVAL The given event mask contains no valid events; or mask  contains
              both  IN_MASK_ADD  and  IN_MASK_CREATE;  or fd is not an inotify
              file descriptor.

              pathname is too long.

       ENOENT A directory component in pathname does not exist or  is  a  dan-
              gling symbolic link.

       ENOMEM Insufficient kernel memory was available.

       ENOSPC The  user  limit  on  the  total  number  of inotify watches was
              reached or the kernel failed to allocate a needed resource.

              mask contains IN_ONLYDIR and pathname is not a directory.

       Inotify was merged into the 2.6.13 Linux kernel.

       This system call is Linux-specific.

       See inotify(7).

       inotify_init(2), inotify_rm_watch(2), inotify(7)

       This page is part of release 5.07 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

Linux                             2020-04-11              INOTIFY_ADD_WATCH(2)

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