Getting page size on POSIX system.

page_size.go

// +build !windows

package main

import (
        "fmt"
        "log"
)

/*
#include <errno.h>
#include <string.h>
#include <unistd.h>

int getErrno(void) {
        return errno;
}

*/
import "C"

func main() {
        sz, err := getPageSize()
        if err != nil {
                log.Fatal(err)
        }
        fmt.Printf("Page size: %d\n", sz)
}

func getPageSize() (int, error) {
        sz := int(C.sysconf(C._SC_PAGESIZE))
        errno := C.getErrno()
        if errno == C.EINVAL {
                return -1, fmt.Errorf("C.sysconf: %s", C.GoString(C.strerror(errno)))
        }
        return sz, nil
}

This program does not work on Windows. On RHEL 6 Linux and macOS Sierra it outputs:

$ go run page_size.go
Page size: 4096