my solution to lab5

lab/user/echo.c

@@ -0,0 +1,21 @@
+#include <inc/lib.h>
+
+void
+umain(int argc, char **argv)
+{
+	int i, nflag;
+
+	nflag = 0;
+	if (argc > 1 && strcmp(argv[1], "-n") == 0) {
+		nflag = 1;
+		argc--;
+		argv++;
+	}
+	for (i = 1; i < argc; i++) {
+		if (i > 1)
+			write(1, " ", 1);
+		write(1, argv[i], strlen(argv[i]));
+	}
+	if (!nflag)
+		write(1, "\n", 1);
+}