Running ".../buildagent/bin/agent.sh start" (starting buildagent) gives next error:
uname: illegal option -- o
usage: uname [-amnprsv]

Though, it still starts agent.

Digging into "agent.sh" showed that it is caused by next code:
CYGWIN=`uname -o`

As "-o" options for "uname" command is not available on Mac OS X , it gives such error.