man2/inotify_add_watch.2

   1 .\" Copyright (C) 2005 Robert Love
   2 .\" and Copyright, 2006 Michael Kerrisk
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  23 .\" 2005-07-19 Robert Love <rlove@rlove.org> - initial version
  24 .\" 2006-02-07 mtk, various changes
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  26 .TH INOTIFY_ADD_WATCH 2 2010-10-20 "Linux" "Linux Programmer's Manual"
  27 .SH NAME
  28 inotify_add_watch \- add a watch to an initialized inotify instance
  29 .SH SYNOPSIS
  30 .B #include <sys/inotify.h>
  31 .sp
  32 .BI "int inotify_add_watch(int " fd ", const char *" pathname ", uint32_t " mask );
  33 .SH DESCRIPTION
  34 .BR inotify_add_watch ()
  35 adds a new watch, or modifies an existing watch,
  36 for the file whose location is specified in
  37 .IR pathname ;
  38 the caller must have read permission for this file.
  39 The
  40 .I fd
  41 argument is a file descriptor referring to the
  42 inotify instance whose watch list is to be modified.
  43 The events to be monitored for
  44 .I pathname
  45 are specified in the
  46 .I mask
  47 bit-mask argument.
  48 See
  49 .BR inotify (7)
  50 for a description of the bits that can be set in
  51 .IR mask .
  52
  53 A successful call to
  54 .BR inotify_add_watch ()
  55 returns the unique watch descriptor associated with
  56 .I pathname
  57 for this inotify instance.
  58 If
  59 .I pathname
  60 was not previously being watched by this inotify instance,
  61 then the watch descriptor is newly allocated.
  62 If
  63 .I pathname
  64 was already being watched, then the descriptor
  65 for the existing watch is returned.
  66
  67 The watch descriptor is returned by later
  68 .BR read (2)s
  69 from the inotify file descriptor.
  70 These reads fetch
  71 .I inotify_event
  72 structures (see
  73 .BR inotify (7))
  74 indicating file system events;
  75 the watch descriptor inside this structure identifies
  76 the object for which the event occurred.
  77 .SH RETURN VALUE
  78 On success,
  79 .BR inotify_add_watch ()
  80 returns a nonnegative watch descriptor.
  81 On error \-1 is returned and
  82 .I errno
  83 is set appropriately.
  84 .SH ERRORS
  85 .TP
  86 .B EACCES
  87 Read access to the given file is not permitted.
  88 .TP
  89 .B EBADF
  90 The given file descriptor is not valid.
  91 .TP
  92 .B EFAULT
  93 .I pathname
  94 points outside of the process's accessible address space.
  95 .TP
  96 .B EINVAL
  97 The given event mask contains no valid events; or
  98 .I fd
  99 is not an inotify file descriptor.
 100 .TP
 101 .B ENOENT
 102 A directory component in
 103 .I pathname
 104 does not exist or is a dangling symbolic link.
 105 .TP
 106 .B ENOMEM
 107 Insufficient kernel memory was available.
 108 .TP
 109 .B ENOSPC
 110 The user limit on the total number of inotify watches was reached or the
 111 kernel failed to allocate a needed resource.
 112 .SH VERSIONS
 113 Inotify was merged into the 2.6.13 Linux kernel.
 114 .SH CONFORMING TO
 115 This system call is Linux-specific.
 116 .SH SEE ALSO
 117 .BR inotify_init (2),
 118 .BR inotify_rm_watch (2),
 119 .BR inotify (7)