free disk space #include <sys/statfs.h> problem

how can i include <sys/statfs.h> to my program.
i have already included but Momentics says :

“sys/statfs.h: No such file or directory Main.cpp”

what should i do?

Heu this is a QNX2/QNX4 forum, Momentics is only for QNX6. sys/statfs.h doesn`t exist under QNX6 which explains the error.