Make pipes blocking

src/user/app/shell/shell.c

@@ -108,16 +108,14 @@ uint64_t main() {
   char chunk[64];
   uint64_t received;
 
-  while (1) {
-    if ((received = read(0, sizeof(chunk), chunk))) {
-      for (uint64_t i = 0; i < received; i++) {
-        if (chunk[i] == '\n') {
-          line[offset] = '\0';
-          execute(line);
-          offset = 0;
-        } else if (offset < 255) {
-          line[offset++] = chunk[i];
-        }
+  while ((received = read(0, sizeof(chunk), chunk))) {
+    for (uint64_t i = 0; i < received; i++) {
+      if (chunk[i] == '\n') {
+        line[offset] = '\0';
+        execute(line);
+        offset = 0;
+      } else if (offset < 255) {
+        line[offset++] = chunk[i];
       }
     }
   }