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 nonnegative watch descriptor.  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.

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

       EINVAL The given event mask contains no valid  events;  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.

VERSIONS

       Inotify was merged into the 2.6.13 Linux kernel.

CONFORMING TO

       This system call is Linux-specific.

SEE ALSO

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

COLOPHON

       This page is part of release 4.15 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/.