ipmitool is linux app that speaks the ipmi protocol to local and remote servers. Here are some example commands to get you started (read the extensive man page for more info):

Get a serial-over-lan console on rcXX: ipmitool -I lanplus -H rcXXipmi -U ADMIN -a sol activate
Get the power status: ipmitool -I lanplus -H rcXXipmi -U ADMIN chassis status
Reboot a machine: ipmitool -I lanplus -H rcXXipmi -U ADMIN power reset
Force PXE boot on the next boot only: ipmitool -I lanplus -H rcXXipmi -U ADMIN chassis bootdev pxe
(This will cause the machine to reinstall all its software on the next boot)
Reboot the IPMI card: ipmitool -I lanplus -H rcXXipmi -U ADMIN mc reset cold
Get sensor output: ipmitool -I lanplus -H rcXXipmi -U ADMIN sdr list
Get the error log: ipmitool -I lanplus -H rcXXipmi -U ADMIN sel elist
NB: Our SuperMicro machines appear to log SMART failures as OEM #0xff, e.g. ipmi