incron is an inotify-based cron system.
You can make it do stuff (like trigger a script) when files or
directories change, are opened, closed, etc (i.e., “filesystem events”).
You need a 2.6.13 kernel or higher to use it.
# CentOS/RHEL sudo yum install incron --yes # Ubuntu sudo apt-get install incron --yes
The global config file is
/etc/incron.conf. Now make sure you start
the service (might be a good idea to
chkconfig this too):
# CentOS/RHEL service incrond start # Ubuntu /etc/init.d/incron start
You can get a listing of events by issuing:
[root@example ~]# incrontab -t IN_ACCESS,IN_MODIFY,IN_ATTRIB,IN_CLOSE_WRITE,IN_CLOSE_NOWRITE,IN_OPEN, IN_MOVED_FROM,IN_MOVED_TO,IN_CREATE,IN_DELETE,IN_DELETE_SELF,IN_CLOSE, IN_MOVE,IN_ONESHOT,IN_ALL_EVENTS,IN_DONT_FOLLOW,IN_ONLYDIR,IN_MOVE_SELF
You can find an explanation of each in
26 /* the following are legal, implemented events that user-space can watch for */ 27 #define IN_ACCESS 0x00000001 /* File was accessed */ 28 #define IN_MODIFY 0x00000002 /* File was modified */ 29 #define IN_ATTRIB 0x00000004 /* Metadata changed */ 30 #define IN_CLOSE_WRITE 0x00000008 /* Writtable file was closed */ 31 #define IN_CLOSE_NOWRITE 0x00000010 /* Unwrittable file closed */ 32 #define IN_OPEN 0x00000020 /* File was opened */ 33 #define IN_MOVED_FROM 0x00000040 /* File was moved from X */ 34 #define IN_MOVED_TO 0x00000080 /* File was moved to Y */ 35 #define IN_CREATE 0x00000100 /* Subfile was created */ 36 #define IN_DELETE 0x00000200 /* Subfile was deleted */ 37 #define IN_DELETE_SELF 0x00000400 /* Self was deleted */ 38 #define IN_MOVE_SELF 0x00000800 /* Self was moved */
Start editing your incrontab with
incrontab *-e*. Here are some
examples of traps
# Restart the NTP daemon when its config file changes /etc/ntp/ntp.conf IN_MODIFY /sbin/service ntpd restart # Run a script with the absolute path to filename as parameter when it changes (and is closed) /home/nanand/thesis.txt IN_WRITE_CLOSE /home/nanand/bin/log_changes.sh $@/$#
Here is a full list of wildcards:
$$ - a dollar sign $@ - the watched filesystem path $# - the event-related file name $% - the event flags (textually) $& - the event flags (numerically)