ulimit is a shell builtin.
http://en.wikipedia.org/wiki/Shell_builtin
http://www.gnu.org/software/bash/manual/html_node/Bash-Builtins.html
Try:
http://en.wikipedia.org/wiki/Shell_builtin
http://www.gnu.org/software/bash/manual/html_node/Bash-Builtins.html
Try:
string command = "bash -c \"ulimit && Parameters[2].ToString\"";