inotifywait, fsnotifywait - wait for changes to files using inotify or fanotify
inotifywait [
-hcmrPq] [
-e <event> ] [
-t
<seconds> ] [
--format <fmt> ] [
--timefmt <fmt>
] <file> [ ... ]
fsnotifywait [
-hcmrPqIFS] [
-e <event> ] [
-t
<seconds> ] [
--format <fmt> ] [
--timefmt <fmt>
] <file> [ ... ]
inotifywait efficiently waits for changes to files using Linux's
inotify(7) interface. It is suitable for waiting for changes to files
from shell scripts. It can either exit once an event occurs, or continually
execute and output events as they occur.
fsnotifywait is similar to
inotifywait but it is using Linux's
fanotify(7) interface by default. If explicitly specified, it uses the
inotify(7) interface.
inotifywait and
fsnotifywait will output diagnostic information on
standard error and event information on standard output. The event output can
be configured, but by default it consists of lines of the following form:
watched_filename EVENT_NAMES event_filename
- watched_filename
- is the name of the file on which the event occurred. If the
file is a directory, a trailing slash is output.
- EVENT_NAMES
- are the names of the inotify events which occurred,
separated by commas.
- event_filename
- is output only when the event occurred on a directory, and
in this case the name of the file within the directory which caused this
event is output.
By default, any special characters in filenames are not escaped in any way.
This can make the output of inotifywait difficult to parse in awk scripts
or similar. The --csv and --format options will be helpful
in this case.
- -h, --help
- Output some helpful usage information.
- @<file>
- When watching a directory tree recursively, exclude the
specified file from being watched. The file must be specified with a
relative or absolute path according to whether a relative or absolute path
is given for watched directories. If a specific path is explicitly both
included and excluded, it will always be watched.
Note: If you need to watch a directory or file whose name starts with
@, give the absolute path.
- --fromfile <file>
- Read filenames to watch or exclude from a file, one
filename per line. If filenames begin with @ they are excluded as
described above. If <file> is `-', filenames are read from standard
input. Use this option if you need to watch too many files to pass in as
command line arguments.
- -m, --monitor
- Instead of exiting after receiving a single event, execute
indefinitely. The default behaviour is to exit after the first event
occurs.
- -d, --daemon
- Same as --monitor, except run in the background logging
events to a file that must be specified by --outfile. Implies
--syslog.
- -o, --outfile <file>
- Output events to <file> rather than stdout.
- -s, --syslog
- Output errors to syslog(3) system log module rather
than stderr.
- -P, --no-dereference
- Do not follow symlinks.
- -r, --recursive
- Watch all subdirectories of any directories passed as
arguments. Watches will be set up recursively to an unlimited depth.
Symbolic links are not traversed. Newly created subdirectories will also
be watched.
Warning: If you use this option while watching the root directory of
a large tree, it may take quite a while until all inotify watches are
established, and events will not be received in this time. Also, since one
inotify watch will be established per subdirectory, it is possible that
the maximum amount of inotify watches per user will be reached. The
default maximum is 8192; it can be increased by writing to
/proc/sys/fs/inotify/max_user_watches.
- -q, --quiet
- If specified once, the program will be less verbose.
Specifically, it will not state when it has completed establishing all
inotify watches.
If specified twice, the program will output nothing at all, except in the
case of fatal errors.
- --exclude <pattern>
- Do not process any events for the subset of files whose
filenames match the specified POSIX regular expression, case sensitive.
- --excludei <pattern>
- Do not process any events for the subset of files whose
filenames match the specified POSIX regular expression, case insensitive.
- --include <pattern>
- Process events only for the subset of files whose filenames
match the specified POSIX regular expression, case sensitive.
- --includei <pattern>
- Process events only for the subset of files whose filenames
match the specified POSIX regular expression, case insensitive.
- -t <seconds>, --timeout <seconds>
- Exit if an appropriate event has not occurred within
<seconds> seconds. If <seconds> is zero (the default), wait
indefinitely for an event.
- -e <event>, --event <event>
- Listen for specific event(s) only. The events which can be
listened for are listed in the EVENTS section. This option can be
specified more than once. If omitted, all events are listened for.
- -c, --csv
- Output in CSV (comma-separated values) format. This is
useful when filenames may contain spaces, since in this case it is not
safe to simply split the output at each space character.
- --timefmt <fmt>
- Set a time format string as accepted by strftime(3) for use
with the `%T' conversion in the --format option.
- --no-newline
- Don't print newline symbol after user-specified format in
the --format option.
- --format <fmt>
- Output in a user-specified format, using printf-like
syntax. The event strings output are limited to around 4000 characters and
will be truncated to this length. The following conversions are supported:
- %w
- This will be replaced with the name of the Watched file on
which an event occurred. When an event occurs within a Watched directory
or when watching with fanotify, this will be replaced with the name of the
Directory in which the event occurred.
- %f
- When an event occurs within a Watched directory or when
watching with fanotify, this will be replaced with the name of the File
which caused the event to occur. Otherwise, this will be replaced with an
empty string.
- %e
- Replaced with the Event(s) which occurred, comma-separated.
- %Xe
- Replaced with the Event(s) which occurred, separated by
whichever character is in the place of `X'.
- %T
- Replaced with the current Time in the format specified by
the --timefmt option, which should be a format string suitable for passing
to strftime(3).
- %0
- Replaced with NUL.
- %n
- Replaced with Line Feed.
The following additional options are available:
- -I, --inotify
- Watch using inotify.
- -F, --fanotify
- Watch using fanotify (default). fanotify support for
reporting events with inotify compatible information was added in kernel
v5.9. With older kernels the command will fail. As of kernel v5.12,
fanotify requires admin privileges.
- -S, --filesystem
- Watch entire filesystem of any directories passed as
arguments using fanotify.
- 0
- The program executed successfully, and an event occurred
which was being listened for.
- 1
- An error occurred in execution of the program, or an event
occurred which was not being listened for. The latter generally occurs if
something happens which forcibly removes the inotify watch, such as a
watched file being deleted or the filesystem containing a watched file
being unmounted.
- 2
- The -t option was used and an event did not occur in
the specified interval of time.
The following events are valid for use with the
-e option:
- access
- A watched file or a file within a watched directory was
read from.
- modify
- A watched file or a file within a watched directory was
written to.
- attrib
- The metadata of a watched file or a file within a watched
directory was modified. This includes timestamps, file permissions,
extended attributes etc.
- close_write
- A watched file or a file within a watched directory was
closed, after being opened in writable mode. This does not necessarily
imply the file was written to.
- close_nowrite
- A watched file or a file within a watched directory was
closed, after being opened in read-only mode.
- close
- A watched file or a file within a watched directory was
closed, regardless of how it was opened. Note that this is actually
implemented simply by listening for both close_write and
close_nowrite, hence all close events received will be output as
one of these, not CLOSE.
- open
- A watched file or a file within a watched directory was
opened.
- moved_to
- A file or directory was moved into a watched directory.
This event occurs even if the file is simply moved from and to the same
directory.
- moved_from
- A file or directory was moved from a watched directory.
This event occurs even if the file is simply moved from and to the same
directory.
- move
- A file or directory was moved from or to a watched
directory. Note that this is actually implemented simply by listening for
both moved_to and moved_from, hence all move events received
will be output as one or both of these, not MOVE.
- move_self
- A watched file or directory was moved. After this event,
the file or directory is no longer being watched.
- create
- A file or directory was created within a watched directory.
- delete
- A file or directory within a watched directory was deleted.
- delete_self
- A watched file or directory was deleted. After this event
the file or directory is no longer being watched. Note that this event can
occur even if it is not explicitly being listened for.
- unmount
- The filesystem on which a watched file or directory resides
was unmounted. After this event the file or directory is no longer being
watched. Note that this event can occur even if it is not explicitly being
listened to.
Running inotifywait at the command-line to wait for any file in the `test'
directory to be accessed. After running inotifywait, `cat test/foo' is run in
a separate console.
% inotifywait test
Setting up watches.
Watches established.
test/ ACCESS foo
A short shell script to efficiently wait for httpd-related log messages and do
something appropriate.
#!/bin/sh
while ! inotifywait -e modify /var/log/messages; do
if tail -n1 /var/log/messages | grep httpd; then
kdialog --msgbox "Apache needs love!"
fi
done
A custom output format is used to watch `~/test'. Meanwhile, someone runs `touch
~/test/badfile; touch ~/test/goodfile; rm ~/test/badfile' in another console.
% inotifywait -m -r --format '%:e %f' ~/test
Setting up watches. Beware: since -r was given, this may take a while!
Watches established.
CREATE badfile
OPEN badfile
ATTRIB badfile
CLOSE_WRITE:CLOSE badfile
CREATE goodfile
OPEN goodfile
ATTRIB goodfile
CLOSE_WRITE:CLOSE goodfile
DELETE badfile
Enforce file permissions in directory `~/test'
inotifywait -qmr -e 'moved_to,create' --format '%w%f%0' --no-newline ~/test |\
while IFS= read -r -d '' file
do
chmod -v a+rX "$file"
done
When using inotifywait, the filename that is outputted is not guaranteed to be
up to date after a move because it is the inode that is being monitored.
Additionally, none of the observed operations are guaranteed to have been
performed on the filename inotifywait was instructed to monitor in cases when
the file is known by several names in the filesystem.
There are race conditions in the recursive directory watching code which can
cause events to be missed if they occur in a directory immediately after that
directory is created. This is probably not fixable.
It is assumed the inotify event queue will never overflow.
inotifywait was started by Rohan McGovern, and is currently maintained by Eric
Curtin and Radu Voicilas.
https://www.openhub.net/p/inotify-tools/contributors/summary gives you a more
complete list of contributors.
inotifywait is part of inotify-tools. The inotify-tools website is located at:
https://github.com/inotify-tools/inotify-tools/wiki
inotifywatch(1),
strftime(3),
inotify(7)