Execute script/program when file changes

Question

Is there a way to set something like a trigger on a file, so that everytime the file is changed a script or program will be executed?

I only found a mechanism for this within a shell script but would like to know if there is a mechanism for that on operating system basis (so that I don't have to manually run a background program). A solution on operating system basis would be a cron-job that runs every few seconds, but this does not look like an adequate solution to me.

It is for Debian, btw.

Thanks for help.

Answer 1

one of your options is the inotify subsystem of the linux kernel:

inotify is a Linux kernel subsystem that acts to extend filesystems to notice changes to the filesystem, and report those changes to applications

but since inotify is kernel-land, you need something in user-space to actually use it:

• inchron:

The inotify cron daemon (incrond) is a daemon which monitors filesystem events and executes commands defined in system and user tables. It's use is generally similar to cron(8).

• gamin:

Gamin is a monitoring system for files and directories that independently implements a subset of FAM, the File Alteration Monitor. Running as a service, it allows for the detection of modifications to a file or directory. gam_server functions as a daemon for Gamin.

• 'inoticoming':

inoticoming - trigger actions when files hit an incoming directory

there was an answer to a similar question on askubuntu:

http://askubuntu.com/a/43848/1223