The man page for fork shows that it needs the unistd.h
header file.  This should be changed to sys/types.h.  A test
compile shows this:


#include <unistd.h>

int bozo(void)
{
	pid_t ret;
	ret = fork();
}


The compile line is: gcc -D_POSIX_SOURCE -c foo.c

> gcc -v
Reading specs from
/usr/lib/gcc-lib/i386-redhat-linux/egcs-2.91.66/specs
gcc version egcs-2.91.66 19990314/Linux (egcs-1.1.2 release)