Ubuntu Manpage: inotifywait, fsnotifywait - wait for changes to files using inotify or fanotify

Provided by: inotify-tools_3.22.1.0-2_amd64

NAME

       inotifywait, fsnotifywait - wait for changes to files using inotify or fanotify

SYNOPSIS

       inotifywait [-hcmrPq] [-e <event> ] [-t <seconds> ] [--format <fmt> ] [--timefmt <fmt> ] <file> [ ... ]

       fsnotifywait [-hcmrPqIFS] [-e <event> ] [-t <seconds> ] [--format <fmt> ] [--timefmt <fmt> ] <file> [ ...
       ]

DESCRIPTION

       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.

OUTPUT

       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.

OPTIONS

-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.

fsnotifywait
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.

EXIT STATUS

       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.

EVENTS

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.

EXAMPLES

   Example 1
       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

   Example 2
       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

   Example 3
       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

   Example 4
       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

CAVEATS

       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.

BUGS

       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.

AUTHORS

       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