i/o redirection in sh

better parsing of sh commands (copied from jos sh)
cat: read from 1 if no args
sbrk system call, but untested
getpid system call
moved locks in keyboard intr, but why do we get intr w. null characters from keyboard?

1 files changed, 4 insertions, 0 deletions

diff --git a/userfs.c b/userfs.c
index 25dfaf5..d1cd49e 100644
--- a/userfs.c
+++ b/userfs.c
@@ -20,6 +20,10 @@ main(void)
 
   printf(stdout, "userfs is running\n");
 
+  if (sbrk(4096) < 0) {
+    printf(stdout, "sbrk failed\n");
+  }
+
   fd = open("echo", 0);
   if(fd >= 0){
     printf(stdout, "open echo ok\n");