NAME

       inotify_add_watch - add a watch to an initialized inotify instance

LIBRARY

       Standard C library (libc, -lc)

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 to indicate the error.

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.

STANDARDS

       Linux.

HISTORY

       Linux 2.6.13.

EXAMPLES

       See inotify(7).

SEE ALSO

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