NAME

       inotify_add_watch - add a watch to an initialized inotify instance

SYNOPSIS

       #include <sys/inotify.h>

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

DESCRIPTION

       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
       descriptor  referring  to  the  inotify  instance  whose  watch list is to be modified.  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 descriptor for this inotify instance, for
       the  filesystem object (inode) that corresponds to pathname.  If the filesystem object was not previously
       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 inotify(7)) indicating filesystem events; the watch descriptor inside this
       structure identifies the object for which the event occurred.

RETURN VALUE

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

ERRORS

       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 already being watched by the same fd.

       EFAULT pathname points outside of the process's accessible address space.

       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.

       ENAMETOOLONG
              pathname is too long.

       ENOENT A directory component in pathname does not exist or is a dangling 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.

       ENOTDIR
              mask contains IN_ONLYDIR and pathname is not a directory.

VERSIONS

       Inotify was merged into the 2.6.13 Linux kernel.

CONFORMING TO

       This system call is Linux-specific.

EXAMPLES

       See inotify(7).

SEE ALSO

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

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/.

Linux                                              2020-04-11                               INOTIFY_ADD_WATCH(2)