[git] Should you commit .gitignore into the Git repos?

I put commit .gitignore, which is a courtesy to other who may build my project that the following files are derived and should be ignored.

I usually do a hybrid. I like to make makefile generate the .gitignore file since the makefile will know all the files associated with the project -derived or otherwise. Then have a top level project .gitignore that you check in, which would ignore the generated .gitignore files created by the makefile for the various sub directories.

So in my project, I might have a bin sub directory with all the built executables. Then, I'll have my makefile generate a .gitignore for that bin directory. And in the top directory .gitignore that lists bin/.gitignore. The top one is the one I check in.