Roger has it correct. psc is the binary but psclient is the wrapper that loads the correct env variables and the like. If you aren't sure where its installed, try the following procedure:
As root (or with a sudo based distro, sudo):
locate -uAnd wait, after a while (long if your drive is huge) then just enter:
locate psclient for an instant search of your hard drive. It will return the path, for example mine returns:
/opt/PlaneShift/psclient so I enter that directory:
cd /opt/PlaneShiftand run
./psclientor alternatively just run with direct path:
/opt/PlaneShift/psclientI hope that helps

Update: Thanks to Bilbous for pointing out the typo. I was totally typing stuff backwards!
