inotify_add_watch(2) System Calls Manual inotify_add_watch(2)
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 re-
ferring 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 descrip-
tor 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 nonnega-
tive 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 al-
ready 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)
Linux man-pages 6.9.1 2024-05-02 inotify_add_watch(2)
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