头文件： #include <unistd.h>
原型：long sysconf(int sysnum);
示例：
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main() {
printf("Size of a page in bytes:%ld ",sysconf(_SC_PAGESIZE));
printf("Max length of a hostname:%ld ",sysconf(_SC_HOST_NAME_MAX));
printf(" The maximum number of files that a process can have open at any time.:%ld ",sysconf(_SC_OPEN_MAX));
printf(" The number of clock ticks per second.:%ld ",sysconf(_SC_CLK_TCK));
printf("The number of processors currently online .:%ld ",sysconf(_SC_NPROCESSORS_ONLN)); printf("The number of processors configured..:%ld ",sysconf(_SC_NPROCESSORS_CONF));
return 0;
}