inotify_add_watch - add a watch to an initialized inotify instance
Standard C library (libc, -lc)
#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 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.
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.
See inotify(7).
Read access to the given file is not permitted.
The given file descriptor is not valid.
mask contains IN_MASK_CREATE and
pathname refers to a file already being watched by the same
fd.
pathname points outside of the process's accessible address
space.
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.
A directory component in pathname does not exist or is a
dangling symbolic link.
Insufficient kernel memory was available.
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.
Linux.
Linux 2.6.13.
inotify_init(2), inotify_rm_watch(2), inotify(7)