diff --git a/.gitignore b/.gitignore
index 2182f77..440553c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@
 *.swp
 *.o
 bmon*
+!bmon.c
diff --git a/bmon.c b/bmon.c
index bdf9369..fb6f20e 100644
--- a/bmon.c
+++ b/bmon.c
@@ -1,10 +1,83 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <dirent.h>
+#include <poll.h>
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
 
-char *bat_power_path = "/sys/class/power_supply/BAT1/energy_now";
-char *bat_capacity_path =  "/sys/class/power_supply/BAT1/capacity";
+//char *bat_power_path = "/sys/class/power_supply/BAT1/energy_now";
+//char *bat_capacity_path =  "/sys/class/power_supply/BAT1/capacity";
+
+const char *bat_base_path = "/sys/class/power_supply/";
+
+void usage (void)
+{
+	printf("usage: bmon [-w]\n");
+}
 
 int main (int argc, char *argv[])
 {
+	int wflag = 0;
+	int opc;
+	while ((opc = getopt(argc, argv, "w")) != -1) {
+		switch (opc) {
+		case 'w':
+			wflag = 1;
+			break;
+		default: /* '?' */
+			usage();
+			exit(1);
+		break; 
+		}
+		
+	}
+
+	DIR *bdir = NULL;
+	if (!(bdir = opendir(bat_base_path)))
+		perror("error opening base directory");
+	
+	struct dirent *ent = NULL;
+	int *fd_list = NULL;
+	int fd_num = 0;
+	for (;;) {
+		errno = 0;
+		if (!(ent = readdir(bdir))) {
+			if (errno)
+				perror("error reading base directory");
+			else break;
+		}
+		
+		if (!strstr(ent->d_name, "BAT1"))
+			continue;
+
+		int fd;
+		char path[sizeof(bat_base_path) + 256 + 64];
+		strcpy(path, bat_base_path);
+		strcat(path, ent->d_name);
+		if (wflag)
+			strcat(path, "/energy_now");
+		else strcat(path, "/capacity");
+
+		if ((fd = open(path, O_RDONLY | O_NONBLOCK)) != -1) {
+			int *tmp = NULL;
+			tmp = realloc(fd_list, sizeof(int) * (fd_num + 1));
+			if (!tmp)
+				perror("failed realloc");
+			fd_list = tmp;
+			fd_list[fd_num] = fd;
+			fd_num++;
+		} else printf("err: %s\n", strerror(errno));
+				
+	}
+	closedir(bdir);
+	if (!fd_num)
+		printf("no files were opened\n");
+	
+	for (int i = 0; i < fd_num; i++)
+		close(fd_list[i]);
 	return 0;
 }
diff --git a/makefile b/makefile
new file mode 100644
index 0000000..1ae9683
--- /dev/null
+++ b/makefile
@@ -0,0 +1,12 @@
+CC = gcc
+CFLAGS = -Wall -Werror -pedantic -O2
+
+bmon: bmon.o
+
+debug:
+	gcc $(CFLAGS) -g bmon.c -o bmon-dbg
+
+bmon.o: bmon.c
+
+clean:
+	rm *.o bmon bmon-dbg 2> /dev/null