inotify_add_watch()

Add or update a watch for filesystem events associated with a path

Synopsis:

#include <sys/inotify.h>

int inotify_add_watch( int fd,
                       const char *pathname,
                       int mask );

Arguments:

fd
A valid file descriptor returned by inotify_init().
path
The path whose filesystem events you want to monitor.
mask
A bitmask that specifies the events you want to watch. The bits include:
  • IN_ACCESS — the file was read.
  • IN_MODIFY — the file was written to.
  • IN_ATTRIB — the attributes of the file changed.
  • IN_CLOSE_WRITE — a file that was opened for writing was closed.
  • IN_CLOSE_NOWRITE — a file that was opened not for writing was closed.
  • IN_CLOSE — the same as (IN_CLOSE_WRITE | IN_CLOSE_NOWRITE).
  • IN_OPEN — the file was opened.
  • IN_MOVED_FROM — the file was moved or renamed away from the item being watched.
  • IN_MOVED_TO — the file was moved or renamed to the item being watched.
  • IN_MOVE — the same as (IN_MOVED_FROM | IN_MOVED_TO).
  • IN_CREATE — a file was created in a watched directory.
  • IN_DELETE — a file or directory was deleted.
  • IN_DELETE_SELF — the file or directory being monitored was deleted.
  • IN_MOVE_SELF — the file or directory being monitored was moved or renamed.

IN_ALL_EVENTS is a bitwise-OR of all the event types.

You can OR the following into the event type:

  • IN_ONESHOT — remove the watch during the generation of the first event.
  • IN_ONLYDIR — watch the pathname only if it's a directory.
  • IN_DONT_FOLLOW — don't dereference the pathname if it's a symbolic link.
  • IN_EXCL_UNLINK — don't generate events for children after they've been unlinked from the watched directory.
  • IN_MASK_ADD — add events to the watch mask (if one already exists) for this pathname, instead of replacing it.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The inotify_add_watch() function starts watching for filesystem events associated with the given path.

For an overview of inotify, see http://www.linuxjournal.com/article/8478?page=0,0 in the Linux Journal, but note that there are differences between the Linux and QNX Neutrino implementations.

Returns:

A watch descriptor, or -1 if an error occurred (errno is set).

Classification:

Linux

Safety:  
Cancellation point No
Interrupt handler No
Signal handler No
Thread Yes