--- doc/bash.1
+++ doc/bash.1
@@ -2035,6 +2035,13 @@
 be a prefix of a stopped job's name; this provides functionality
 analogous to the \fB%\fP\fIstring\fP job identifier.
 .TP
+.B command_not_found_handle
+The name of a shell function to be called if a command cannot be
+found. The return value of this function should be 0, if the command
+is available after execution of the function, otherwise 127 (EX_NOTFOUND).
+Enabled only in interactive, non POSIX mode shells. This is a Debian
+extension.
+.TP
 .B histchars
 The two or three characters which control history expansion
 and tokenization (see
--- doc/bashref.texi
+++ doc/bashref.texi
@@ -4809,6 +4809,13 @@
 @item UID
 The numeric real user id of the current user.  This variable is readonly.
 
+@item command_not_found_handle
+The name of a shell function to be called if a command cannot be
+found. The return value of this function should be 0, if the command
+is available after execution of the function, otherwise 127 (EX_NOTFOUND).
+Enabled only in interactive, non POSIX mode shells. This is a Debian
+extension.
+
 @end vtable
 
 @node Bash Features
--- execute_cmd.c
+++ execute_cmd.c
@@ -3722,8 +3722,26 @@
 
       if (command == 0)
 	{
-	  internal_error (_("%s: command not found"), pathname);
-	  exit (EX_NOTFOUND);	/* Posix.2 says the exit status is 127 */
+	  SHELL_VAR *f, *v;
+	  WORD_LIST *cmdlist;
+	  WORD_DESC *w;
+	  int fval;
+	  if( (posixly_correct || interactive_shell == 0) ||
+	      (f = find_function ("command_not_found_handle")) == 0)
+	    {
+	      internal_error (_("%s: command not found"), pathname);
+	      exit (EX_NOTFOUND);     /* Posix.2 says the exit status is 127 */
+	    }
+	  w = make_word("command_not_found_handle");
+	  cmdlist = make_word_list(w, (WORD_LIST*)NULL);
+
+	  w = make_word(pathname);
+	  cmdlist->next = make_word_list(w, (WORD_LIST*)NULL);
+	   
+	  fval = execute_shell_function (f, cmdlist);
+	  if (fval == EX_NOTFOUND)
+	    internal_error (_("%s: command not found"), pathname);
+	  exit(fval);
 	}
 
       /* Execve expects the command name to be in args[0].  So we