inotify cron system

(c) Andreas Altair Redmer, 2014, 2015
Lukas Jelinek, 2006, 2007, 2008, 2009, 2012

Content

1. About
2. Install a binary version
3. Obtain the source code
4. Requirements
5. How to build
6. How to use
7. Bugs, suggestions
8. Licensing

1. About

This program is the "inotify cron" system. It consist of a daemon and a table manipulator. You can use it a similar way as the regular cron. The difference is that the inotify cron handles filesystem events rather than time periods.

This project was kicked off by Lukas Jelinek in 2006 and then unfortunatally abandoned in 2012. Upstream development and bug-tracking/fixing continued in 2014 on GitHub: https://github.com/ar-/incron .

2. Install a binary version

On Debian and Ubuntu based systems you can install this software (the version maintained by Debian) with sudo apt-get install incron

There is a daily build running on Launchpad. You can install that build from a PPA in Ubuntu, to have always an up-to-date build.

sudo add-apt-repository ppa:altair-ibn-la-ahad/incron  
sudo apt-get update  
sudo apt-get install incron

For more information follow the link to the PPA:
https://code.launchpad.net/~altair-ibn-la-ahad/+archive/ubuntu/incron

The build logs are available here:
https://code.launchpad.net/~altair-ibn-la-ahad/+recipe/incron-daily

On all other Linux based systems you have to build it from source. If you would like to add a build script for other linux flavors (Gentoo, Suse, Ret Hat, ...) please send me a pull request. I will be happy to include it.

3. Obtain the source code

You can download the latest stable version from https://github.com/ar-/incron/archive/master.tar.gz

You can download older versions from https://github.com/ar-/incron/releases

4. Requirements

• Linux kernel 2.6.13 or later (with inotify compiled in)
• inotify headers (inotify.h, sometimes inotify-syscalls.h) installed in <INCLUDE_DIR>/sys. The most common place is /usr/include/sys.
• GCC 4.x compiler (probably works also with GCC 3.4, possibly with older versions too)

5. How to build

Short:

make -j8 && sudo make install

Long:

This software does not contain a standard portable build mechanism. There is only a Makefile which may be modified manually. On many Linux systems you need not to change anything.

Please review the Makefile BEFORE you type 'make'. Especially check the PREFIX and other common variables. If done you can now build the files ('make').

The binaries must be of course installed as root.

If you want to use (after editing) the example configuration file simply rename it from /etc/incron.conf.example to /etc/incron.conf (you can also use -f for one-time use of a custom configuration file).

Making a release of the source tree relies on the 'VERSION' file. The file should contain only a simple version string such as '0.5.9' or (if you wish) something more comlex (e.g. '0.5.9-improved'). The doxygen program must be installed and its control file 'Doxygen' created for generating the API documentation.

6. How to use

The incron daemon (incrond) must be run under root (typically from runlevel script etc.). It loads the current user tables and hooks them for later changes.

The incron table manipulator may be run under any regular user since it SUIDs. For manipulation with the tables use basically the same syntax as for the crontab program. You can import a table, remove and edit the current table.

The user table rows have the following syntax:

Where:

is a filesystem path (currently avoid whitespaces!) is a symbolic (see inotify.h; use commas for separating symbols) or numeric mask for events is an application or script to run on the events

The command may contain these wildcards:

• $$ - a dollar sign
• $@ - the watched filesystem path (see above)
• $# - the event-related file name
• $% - the event flags (textually)
• $& - the event flags (numerically)

The mask may additionaly contain a special symbol loopable=true which disables events occurred during the event handling (to avoid loops). It also may contain recursive=false to ignore sub-directories. The mask can also be extended by dotdirs=true which will include dotdirectories (hidden directories and hidden files) into the search.

Example 1: You need to run program 'abc' with the full file path as an argument every time a file is changed in /var/mail. One of the solutions follows:

/var/mail IN_CLOSE_WRITE abc $@/$#

Example 2: You need to run program 'efg' with the full file path as the first argument and the numeric event flags as the second one. It have to monitor all events on files in /tmp. Here is it:

/tmp IN_ALL_EVENTS efg $@/$# $&

Since 0.4.0 also system tables are supported. They are located in /etc/incron.d and their commands use root privileges. System tables are intended to be changed directly (without incrontab).

Some parameters of both incrontab and incrond can be changed by the configuration. See the example file for more information.

Example 3: You need to run program 'playmp3' with the full file path as an argument every time a MP3 file is moved to in /home/u1/Music. One of the solutions follows:

/home/u1/Music/*.mp3 IN_MOVED_TO playmp3 $@/$#

Example 4: You need to observe the directory /etc/ recursively and report every change in the syslog. One of the solutions follows:

/etc/ IN_CLOSE_WRITE echo $@/$# | logger

Example 5: You need to observe the directory /etc/apache but exclude the sub-directories and report every change in the syslog. One of the solutions follows:

/etc/apache IN_CLOSE_WRITE,recursive=false echo $@/$# | logger

Example 6: You need to observe the directory /home/user1 recursively, including all the hidden sub-directories and hidden files (dotfiles/dotdirectories) and report every change in the syslog. One of the solutions follows:

/home/user1 IN_CLOSE_WRITE,dotdirs=true echo $@/$# | logger

7. Bugs, suggestions

incrond is currently not resistent against looping.

If you find a bug or have a suggestion how to improve the program, please use the bug tracking system at https://github.com/ar-/incron/issues.

8. Licensing

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License, version 2 (see LICENSE-GPL).

Some parts may be also covered by other licenses. Please look into the source files for detailed information.