Adding who, chroot, env and split.

Thanks "Galos, David" <galosd83@students.rowan.edu>!

chroot.c

@@ -0,0 +1,38 @@
+#include <stdlib.h>
+#include <unistd.h>
+#include "util.h"
+
+static void usage(void);
+
+int
+main(int argc, char **argv)
+{
+	char *shell[] = {"/bin/sh", "-i", NULL};
+	
+	if(getenv("SHELL"))
+		shell[0] = getenv("SHELL");
+
+	if(argc < 2)
+		usage();
+	
+	if(chroot(argv[1]) == -1)
+		eprintf("chroot: '%s':", argv[1]);
+	
+	if(chdir("/") == -1)
+		eprintf("chroot:");
+
+	if(argc == 2) {
+		execvp(*shell, shell);
+	} else {
+		execvp(argv[2], argv+2);
+	}
+	
+	eprintf("chroot: '%s':", argv[2]);
+	return 1;
+}
+
+void
+usage(void)
+{
+	eprintf("usage: chroot dir [command [arg...]]\n");
+}