inotify_add_watch(2) — Linux manual page

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 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)

COLOPHON

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Linux man-pages 6.9.1          2024-05-02           inotify_add_watch(2)

Pages that refer to this page: inotify_init(2), inotify_rm_watch(2), syscalls(2), inotify(7)

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