Incron – Monitor filesystem events and execute actions


is a daemon which monitors filesystem events and executes commands defined in system and user tables. It can be installed on all major distributions using each distribution’s default package manager.

Why I needed it?

I’m using as a web server for my vps server. That being said, the web root folder where I add files to be accessible via web, due to security reasons it has ownership as: 750 mode for folders and 640 for files. Since I do a lot of copying from one server to another, usually the files that I copy from another server to my server, have a default ownership of root:root (since I login via ssh with a regular user, then sudo su – (too damn lazy to add sudo before every command).

If I want to download that file from my own server via HTTP let’s say, I have to chown : that file (otherwise I’ll get a read error because of the ownership). And this can become annoying sometimes. So I was looking for some sort of solution to be able do that automatically. To be more specific, if a new file is created or copied in my web root folder, then to automatically execute a chown : on that file. I played a little bit with the inotify-tools and inotify-wait but I didn’t like it entirely. Then I decided to use incron.

The syntax is pretty similar with the one from cron (crontab).

The format is as follows:

where can be a directory (meaning the directory and/or the files directly in that directory (not files in subdirectories of that directory!) are watched) or a file.

can be one of the following:

Command takes the following arguments:

For more information please consult the program’s man page.

So let’s take this scenario for example: My web root folder is /var/www/html. So I want to monitor that folder and if a file is copied there, modified, created, edited etc, when that happens, incron will automatically execute /usr/bin/chown nginx:nginx file.

That can be achieved like that:

Then add the entry bellow and save:

Now if a new file is created/edited/modified/copied to the /var/www/html/ folder the /usr/bin/chown : command will be automatically executed on that file.

Pretty simple isn’t it?

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