diff --git a/chp4/mmap.c b/chp4/mmap.c
new file mode 100644
index 0000000..11c9843
--- /dev/null
+++ b/chp4/mmap.c
@@ -0,0 +1,53 @@
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/mman.h>
+
+int main(int argc, char *argv[]) {
+	
+	if (argc < 2) {
+		fprintf(stderr, "usage: %s <file>\n", argv[0]);
+		return 1;
+	}
+
+	int fd = open(argv[1], O_RDONLY);
+	if (fd == -1) {
+		perror("open");
+		return 1;
+	}
+
+	struct stat sb;
+	if (fstat(fd, &sb) == -1) {
+		perror("fstat");
+		return 1;
+	}
+
+	if (!S_ISREG(sb.st_mode)) {
+		fprintf(stderr, "%s is not a file\n", argv[1]);
+		return 1;
+	}
+
+	char *p = (char *)mmap(0, sb.st_size, PROT_READ, MAP_SHARED, fd, 0);
+	if (p == MAP_FAILED) {
+		perror("mmap");
+		return 1;
+	}
+
+	if (close(fd) == -1) {
+		perror("close");
+		return 1;
+	}
+
+	for (int len = 0; len < sb.st_size; len++) {
+		putchar(p[len]);
+	}
+
+	if (munmap(p, sb.st_size) == -1) {
+		perror("munmap");
+		return 1;
+	}
+
+	return 0;
+}