I've done bit of a search but I can't find a way to syncronise the contents of one folder into another which is a back-up folder. I basically want the function of the ln cammand executed on every new file that appears in the source folder and have it also pointing to the backup folder. If the source file disappears, I don't want to lose it from the back-up.
Why I'm after this is so I can create a backup of emails coming in, and going out and users not being able to hide their tracks if something is required for auditing which has happened to us in the past.
Looking at Unison, it appears very similar to rsync. What I was after was something that could syncronise folders as they change automatically.
I know in Windows, if I write a program that hooks into the folder change event, I then know that I need to resync folder contents. My knowledge of Linux isn't that great and I don't know what is possible and if there is a tool already available.