About Incron

Install incron

Type the following command under RHEL / Fedora / CentOS Linux:
$ sudo yum install incron
Type the following command under Debian / Ubuntu Linux:
$ sudo apt-get install incron

Configuration Files

• /etc/incron.conf - Main incron configuration file
• /etc/incron.d/ - This directory is examined by incrond for system table files. You should put all your config file here as per directory or domain names.
• /etc/incron.allow - This file contains users allowed to use incron.
• /etc/incron.deny - This file contains users denied to use incron.
• /var/spool/incron - This directory is examined by incrond for user table files which is set by users running the incrontab command.

incron Syntax

The syntax is as follows:

    options
/var/www/html IN_CREATE /root/scripts/backup.sh
/sales IN_DELETE /root/scripts/sync.sh
/var/named/chroot/var/master IN_CREATE,IN_ATTRIB,IN_MODIFY /sbin/rndc reload

Where,

• - It is nothing but path which is an absolute filesystem path such as /home/data. Any changes made to this path will result into command or action.
• - Mask is is nothing but various file system events such as deleting a file. Each event can result into command execution. Use the following masks:
• IN_ACCESS - File was accessed (read)
• IN_ATTRIB - Metadata changed (permissions, timestamps, extended attributes, etc.)
• IN_CLOSE_WRITE - File opened for writing was closed
• IN_CLOSE_NOWRITE - File not opened for writing was closed
• IN_CREATE - File/directory created in watched directory
• IN_DELETE - File/directory deleted from watched directory
• IN_DELETE_SELF - Watched file/directory was itself deleted
• IN_MODIFY - File was modified
• IN_MOVE_SELF - Watched file/directory was itself moved
• IN_MOVED_FROM - File moved out of watched directory
• IN_MOVED_TO - File moved into watched directory
• IN_OPEN - File was opened
• The IN_ALL_EVENTS symbol is defined as a bit mask of all of the above events.
• - Run command or scripts when mask matched on given directory.
• options - It can be any one of the following with command (i.e. you can pass it as arg to your command):
1. $$ - dollar sign
2. $@ - watched filesystem path (see above)
3. $# - event-related file name
4. $% - event flags (textually)
5. $& - event flags (numerically)

Turn Service On

Type the following command:
# service incrond start
# chkconfig incrond on

Examples:

Type the following command to edit your incrontab
incrontab -e
Run logger command when file created or deleted from /tmp directory:
/tmp IN_ALL_EVENTS logger "/tmp action for $# file"
Save and close the file. Now cd to /tmp and create a file:
$ cd /tmp
$ >foo
$ rm foo