incrontab - tables for driving inotify cron (incron)
An incrontab file contains instructions to the incrond
(8) daemon of the
general form: "run this command on these file events". There are two
categories of tables: system tables (with root privileges) and user tables
(with user privileges).
System tables are (by default) located in /etc/incron.d and may have any names.
Each system table exists separately inside incron and their watches never
Each user has their own table, and commands in any given incrontab will be
executed as the user who owns the incrontab. System users (such as apache,
postfix, nobody etc.) may have their own incrontab.
incrontab files are read when the incrond
(8) daemon starts and after any
change (incrontab file are being hooked when incrond is running).
Blank lines are ignored. The general line format is the following:
<path> <mask> <command>
is an absolute filesystem path, mask
is an event mask
(in symbolic or numeric form) and command
is an executable file (or a
script) with its arguments. See bellow for event mask symbols. The executable
file may be noted as an absolute path or only as the name itself (PATH
locations are examined).
Please remember that the same path may occur only once per table (otherwise only
the first occurrence takes effect and an error message is emitted to the
These basic event mask symbols are defined:
File was accessed (read) (*)
Metadata changed (permissions, timestamps, extended
attributes, etc.) (*)
File opened for writing was closed (*)
File not opened for writing was closed (*)
File/directory created in watched directory (*)
File/directory deleted from watched directory (*)
Watched file/directory was itself deleted
File was modified (*)
Watched file/directory was itself moved
File moved out of watched directory (*)
File moved into watched directory (*)
File was opened (*)
When monitoring a directory, the events marked with an asterisk (*) above can
occur for files in the directory, in which case the name field in the returned
event data identifies the name of the file within the directory.
symbol is defined as a bit mask of all of the above
events. Two additional convenience symbols are IN_MOVE
, which is a
combination of IN_MOVED_FROM
which combines IN_CLOSE_WRITE
The following further symbols can be specified in the mask:
Don't dereference pathname if it is a symbolic link
Monitor pathname for only one event
Only watch pathname if it is a directory
Additionally, there is a symbol which doesn't appear in the inotify symbol set.
It it IN_NO_LOOP
. This symbol disables monitoring events until the
current one is completely handled (until its child process exits).
The following wildards may be used inside command specification:
watched filesystem path (see above)
event-related file name
event flags (textually)
event flags (numerically)
These are some example rules which can be used in an incrontab file:
/tmp IN_ALL_EVENTS abcd $@/$# $%
/usr/bin IN_ACCESS,IN_NO_LOOP abcd $#
/home IN_CREATE /usr/local/bin/abcd $#
/var/log 12 abcd $@/$#
The first line monitors all events on the /tmp directory. When an event occurs
it runs a application called 'abcd' with the full path of the file as the
first arguments and the event flags as the second one.
The second line monitors accesses (readings) on the /usr/bin directory. The
application 'abcd' is run as a handler and the appropriate event watch is
disabled until the program finishes. The file name (without the directory
path) is passed in as an argument.
The third example is used for monitoring the /home directory for newly create
files or directories (it practically means an event is sent when a new user is
added). This event is processed by a program specified by an absolute path.
And the final line shows how to use numeric event mask instead of textual one.
The value 12 is exactly the same as IN_ATTRIB,IN_CLOSE_WRITE.
incrond(8), incrontab(1), incron.conf(5)
Lukas Jelinek <email@example.com> (please report bugs to http://bts.aiken.cz
This program is free software. It can be used, redistributed and/or modified
under the terms of the GNU General Public License, version 2.