add directory study

study/linux-travel/MINIX-1.5/1.5/Source/commands/recover.c

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+/* recover - un-remove a file		Author: Andy Tanenbaum */
+
+/* Unlike most UNIX systems, MINIX provides a way to recover a file that
+ * has been accidently rm'ed.  The recovery is done using Terrence Holm's
+ * 'de' (disk editor) program, plus some patches to FS that keep the i-node
+ * number in the directory, even after the file has been removed.  A file
+ * cannot be recovered after its directory slot has been reused.
+ *
+ * Usage:
+ *	recovery file ...
+ *
+ * Note: the file names must be fully explicit; wild cards are not allowed.
+ * It is not possible, for example, to say recover *.c.  All the files must
+ * be named in full.  Since the last two bytes of the directory entry are
+ * used for the i-node number, only the first 12 characters of the file name
+ * count.  Full 14 character file names can be specified, however, only the
+ * last two characters, in fact, play no role in locating the file.
+ */
+
+main(argc, argv)
+int argc;
+char *argv[];
+{
+  int i;
+  char buf[1024];
+
+  if (argc == 1) usage();
+
+  for (i = 1; i < argc; i++) {
+	strcpy(buf, "de -r ");
+	strcat(buf, argv[i]);
+	system(buf);
+  }
+}
+
+
+usage()
+{
+  std_err("Usage: recover file ...\n");
+  exit(1);
+}