1 files changed, 30 insertions, 0 deletions
diff --git a/src/util/io.cc b/src/util/io.cc
index 531bd47..1261684 100644
--- a/src/util/io.cc
+++ b/src/util/io.cc
@@ -96,4 +96,34 @@ char *itoa(int num, char* str, int base)
     return str;
 }
 
+/*
+ * usage - print a help message
+ */
+void usage(void) 
+{
+    printf("Usage: shell [-hvp]\n");
+    printf("   -h   print this message\n");
+    printf("   -v   print additional diagnostic information\n");
+    printf("   -p   do not emit a command prompt\n");
+    exit(1);
+}
+
+/*
+ * unix_error - unix-style error routine
+ */
+void unix_error(char *msg)
+{
+    fprintf(stdout, "%s: %s\n", msg, strerror(errno));
+    exit(1);
+}
+
+/*
+ * app_error - application-style error routine
+ */
+void app_error(char *msg)
+{
+    fprintf(stdout, "%s\n", msg);
+    exit(1);
+}
+
 }