--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/usr/wc.c	Fri May 26 23:11:05 2017 +0900
@@ -0,0 +1,54 @@
+#include "types.h"
+#include "stat.h"
+#include "user.h"
+
+char buf[512];
+
+void
+wc(int fd, char *name)
+{
+    int i, n;
+    int l, w, c, inword;
+    
+    l = w = c = 0;
+    inword = 0;
+    while((n = read(fd, buf, sizeof(buf))) > 0){
+        for(i=0; i<n; i++){
+            c++;
+            if(buf[i] == '\n')
+                l++;
+            if(strchr(" \r\t\n\v", buf[i]))
+                inword = 0;
+            else if(!inword){
+                w++;
+                inword = 1;
+            }
+        }
+    }
+    if(n < 0){
+        printf(1, "wc: read error\n");
+        exit();
+    }
+    printf(1, "%d %d %d %s\n", l, w, c, name);
+}
+
+int
+main(int argc, char *argv[])
+{
+    int fd, i;
+    
+    if(argc <= 1){
+        wc(0, "");
+        exit();
+    }
+    
+    for(i = 1; i < argc; i++){
+        if((fd = open(argv[i], 0)) < 0){
+            printf(1, "wc: cannot open %s\n", argv[i]);
+            exit();
+        }
+        wc(fd, argv[i]);
+        close(fd);
+    }
+    exit();
+}