incron

incron is a daemon which monitors filesystem events and executes commands defined in system and user tables.

Installation

Install the incron package.

Activation and autostart

After installation, the daemon will not be enabled by default. You can enable incrond.service.

Configuration

Incrontabs should never be edited directly; instead, users should use the incrontab program to work with their incrontabs.

Using incrontab

To view their incrontabs, users should issue the command:

$ incrontab -l

To edit their incrontabs, they should use:

$ incrontab -e

To remove their incrontabs, they may use:

$ incrontab -r

To reload incrond, use:

$ incrontab -d

To edit another user's incrontab, isue the following command as root:

$ incrontab -u user -e

Incrontab format

Each row in an incrontab file is a table that the dameon runs when an event happens to a certain directory or file.

The basic format for an incrontab is:

path mask command

• path is the directory or file that incrond will monitor for changes.
• mask is the type of filesystem event that incrond will monitor for. This paramter can be seperated by commas.
• command is the commmand to be run after the specified filesystem event(s) occur.

Mask types

incrontab uses mask types to specify which file system event to monitor for. For more options see inotify(7)

To trigger an command if a file is accessed or read:

IN_ACCESS

To trigger an command if metadata of a file change (e.g. timestamps, permissons):

IN_ATTRIB

To trigger a command if a file opened for writing is closed:

IN_CLOSE_WRITE

To trigger a command if a file or directory not opened for writing is closed:

IN_CLOSE_NOWRITE

To trigger a command if a file or directory is created in a watched directory:

IN_CREATE

To trigger a command if a file or directory is deleted from a watched directory:

IN_DELETE

To trigger a command if a watched file or directory is deleted (or moved to a different filesystem):

IN_DELETE_SELF

To trigger a command if a file was modified:

IN_MODIFY

To trigger a command if a watched file or directory is moved within the filesystem:

IN_MOVE_SELF

To trigger a command if a file or directory is moved out of the watched directory:

IN_MOVED_FROM

To trigger a command if a file or directory is moved to the watched directory:

IN_MOVED_TO

To trigger a command if a watched file or directory is opened:

IN_OPEN

Custom Mask Types

Incrond provides additional custom event types to modify its monitoring behavior.

For instance, to pause monitoring an event until the current one is completely handled, add loopable=true to the event list, eg:

IN_CLOSE,loopable=true

An event with the loopable event enabled will not fire again until the associated command exits.

See incrontab(5) for the complete list of custom mask types.