mirror of https://github.com/mkerrisk/man-pages
152 lines
3.9 KiB
Groff
152 lines
3.9 KiB
Groff
.\" Copyright (C) 2005 Robert Love
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.\" and Copyright, 2006 Michael Kerrisk
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.\"
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.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
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.\" This is free documentation; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License as
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.\" published by the Free Software Foundation; either version 2 of
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.\" the License, or (at your option) any later version.
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.\"
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.\" The GNU General Public License's references to "object code"
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.\" and "executables" are to be interpreted as the output of any
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.\" document formatting or typesetting system, including
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.\" intermediate and printed output.
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.\"
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.\" This manual is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details.
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.\"
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.\" You should have received a copy of the GNU General Public
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.\" License along with this manual; if not, see
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.\" <http://www.gnu.org/licenses/>.
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.\" %%%LICENSE_END
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.\"
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.\" 2005-07-19 Robert Love <rlove@rlove.org> - initial version
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.\" 2006-02-07 mtk, various changes
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.\"
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.TH INOTIFY_ADD_WATCH 2 2021-03-22 "Linux" "Linux Programmer's Manual"
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.SH NAME
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inotify_add_watch \- add a watch to an initialized inotify instance
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.SH SYNOPSIS
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.nf
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.B #include <sys/inotify.h>
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.PP
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.BI "int inotify_add_watch(int " fd ", const char *" pathname ", uint32_t " mask );
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.fi
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.SH DESCRIPTION
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.BR inotify_add_watch ()
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adds a new watch, or modifies an existing watch,
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for the file whose location is specified in
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.IR pathname ;
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the caller must have read permission for this file.
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The
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.I fd
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argument is a file descriptor referring to the
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inotify instance whose watch list is to be modified.
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The events to be monitored for
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.I pathname
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are specified in the
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.I mask
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bit-mask argument.
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See
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.BR inotify (7)
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for a description of the bits that can be set in
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.IR mask .
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.PP
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A successful call to
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.BR inotify_add_watch ()
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returns a unique watch descriptor for this inotify instance,
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for the filesystem object (inode) that corresponds to
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.IR pathname .
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If the filesystem object
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was not previously being watched by this inotify instance,
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then the watch descriptor is newly allocated.
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If the filesystem object was already being watched
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(perhaps via a different link to the same object), then the descriptor
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for the existing watch is returned.
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.PP
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The watch descriptor is returned by later
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.BR read (2)s
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from the inotify file descriptor.
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These reads fetch
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.I inotify_event
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structures (see
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.BR inotify (7))
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indicating filesystem events;
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the watch descriptor inside this structure identifies
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the object for which the event occurred.
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.SH RETURN VALUE
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On success,
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.BR inotify_add_watch ()
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returns a watch descriptor (a nonnegative integer).
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On error, \-1 is returned and
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.I errno
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is set to indicate the error.
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.SH ERRORS
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.TP
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.B EACCES
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Read access to the given file is not permitted.
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.TP
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.B EBADF
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The given file descriptor is not valid.
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.TP
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.B EEXIST
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.I mask
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contains
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.B IN_MASK_CREATE
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and
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.I pathname
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refers to a file already being watched by the same
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.IR fd .
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.TP
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.B EFAULT
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.I pathname
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points outside of the process's accessible address space.
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.TP
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.B EINVAL
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The given event mask contains no valid events; or
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.I mask
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contains both
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.B IN_MASK_ADD
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and
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.BR IN_MASK_CREATE ;
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or
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.I fd
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is not an inotify file descriptor.
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.TP
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.B ENAMETOOLONG
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.I pathname
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is too long.
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.TP
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.B ENOENT
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A directory component in
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.I pathname
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does not exist or is a dangling symbolic link.
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.TP
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.B ENOMEM
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Insufficient kernel memory was available.
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.TP
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.B ENOSPC
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The user limit on the total number of inotify watches was reached or the
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kernel failed to allocate a needed resource.
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.TP
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.B ENOTDIR
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.I mask
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contains
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.B IN_ONLYDIR
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and
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.I pathname
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is not a directory.
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.SH VERSIONS
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Inotify was merged into the 2.6.13 Linux kernel.
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.SH CONFORMING TO
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This system call is Linux-specific.
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.SH EXAMPLES
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See
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.BR inotify (7).
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.SH SEE ALSO
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.BR inotify_init (2),
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.BR inotify_rm_watch (2),
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.BR inotify (7)
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