Add pagesize(1)

This program is useful in constructing portable shell scripts.

Makefile

@@ -32,6 +32,7 @@ SRC = \
 	mkswap.c            \
 	mount.c             \
 	mountpoint.c        \
+	pagesize.c          \
 	pidof.c             \
 	pivot_root.c        \
 	ps.c                \

pagesize.c

@@ -0,0 +1,31 @@
+/* See LICENSE file for copyright and license details. */
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "util.h"
+
+static void
+usage(void)
+{
+	eprintf("usage: %s\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	long pagesz;
+
+	ARGBEGIN {
+	default:
+		usage();
+	} ARGEND;
+
+	pagesz = sysconf(_SC_PAGESIZE);
+	if (pagesz < 0) {
+		pagesz = sysconf(_SC_PAGE_SIZE);
+		if (pagesz < 0)
+			enprintf(EXIT_FAILURE, "can't determine pagesize\n");
+	}
+	printf("%ld\n", pagesz);
+	return EXIT_SUCCESS;
+}