Where should I put system-wide scripts in *nix system?
Solution 1:
Well, your tags include the Filesystem Hierarchy Standard so that should give you some guidance. I would recommend /usr/local/bin.
Solution 2:
I never put scripts that I write in /usr/bin. Either /usr/local/bin or, preferrably, /opt/local/bin. Virtually nothing's going to collide with or stomp on scripts in the latter.