How to prevent user from changing files using linux permission

Question

Is it possible, using linux permission scheme, to allow users create files but not edit or delete them at a later time? I mean, we have a delivery folder where users put artifacts there and we do not want these artifacts to be modified after delivered i.e. edited or deleted.

Answer 1

You can't do that: if the user can create files, they'll be owned by him, and he'll be able to modify them and erase them.

I was going to propose a simple scheme to have a staging directory (where the user can do what he wants) and an incoming directory (not accessible to the user), with a small privileged program to move files from the staging directory to the incoming directory. But it's actually tricky to do right: amongst other things you need to take care that the privileged program won't move files in other directories (beware of race conditions, symbolic links, ../), won't overwrite existing files (rename(3) is atomic but can erase the destination), won't let the user keep a file descriptor open and modify the file after it's moved (so you'd better copy than move). Instead, I'll recommend to take an existing, robust solution:

• Have the user upload the file over HTTP.
• Have the user commit to a version control system. He'll be able to commit new versions, too.

Answer 2

Is it possible, using linux permission scheme, to allow users create files but not edit or delete them at a later time?

NO

But you have other options as suggested by @Fredrik in the comment to your question. See here.