If I install a package manager such as Macports, Fink or Homebrew, how does it affect the startup and running of my system?
It seems like the answer should be "Not at all when you're not using them" but I'm worried that they will break other software (like Mono) or run background processes. Is my fear totally misplaced? Are they just programs like any others?
They sure seem to put their footprint around the OS in quite a few places.
I can mainly speak for MacPorts, but I'm sure this applies to at least Fink and likely Homebrew as well. There are no background processes at all for the MacPorts package installer. It's just a system that keeps track of installed ports and maintains dependencies in its own self-contained /opt/local directory (with few exceptions). If you install some sort of daemon or service that needs to be run as a background service, then that's a different story and the output of port install will typically give you instructions on how to load it.
I cannot see a way that installing MacPorts (or Fink, etc) would inherently break your Mono installation, which installs itself in /Library/Frameworks with symlinks for executables in /usr/bin. I would say your fear is misplaced.
It is possible to install daemon processes via Fink, MacPorts and Homebrew but in all cases, you need to manually run launchctl to add that process to launchd
You are more likely to cause yourself a problem by manually installing from a source tarball than by a package manager. Or by using two or more package managers. As an example, don't try and install ruby gems via ports and via the gems command since those installed by the gems command are not going to update the ports database of installed gems and vice versa.
