--- a/src/input.cc	Wed Jan 18 15:56:40 1995 +0000
+++ b/src/input.cc	Wed Jan 18 16:35:01 1995 +0000
@@ -45,6 +45,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <iostream.h>
+#include <strstream.h>
 #include <string.h>
 #include <assert.h>
 #include <signal.h>
@@ -429,6 +430,33 @@
   return result;
 }
 
+static void
+do_input_echo (const char *input_string)
+{
+  if (echo_input)
+    {
+      ostrstream buf;
+
+      if (! forced_interactive)
+	{
+	  char *prefix = decode_prompt_string (user_pref.ps4);
+	  buf << prefix;
+	  delete [] prefix;
+	}
+
+      if (input_string)
+	{
+	  buf << input_string;
+	  int len = strlen (input_string);
+	  if (input_string[len-1] != '\n')
+	    buf << "\n";
+	}
+
+      maybe_page_output (buf);
+    }
+}
+
+
 // Use GNU readline to get an input line and store it in the history
 // list.
 
@@ -469,13 +497,7 @@
 
       maybe_write_to_diary_file (octave_gets_line);
 
-      if (echo_input)
-	{
-	  if (! forced_interactive)
-	    cout << "+ ";
-
-	  cout << octave_gets_line << "\n";
-	}
+      do_input_echo (octave_gets_line);
     }
 
   maybe_write_to_diary_file ("\n");
@@ -562,17 +584,14 @@
 	delete [] stashed_line;
 
       stashed_line = strsave (buf);
+
       current_input_line = stashed_line;
 
-      if (echo_input && current_input_line && *current_input_line)
-	{
-	  if (! forced_interactive)
-	    cout << "+ ";
+      do_input_echo (current_input_line);
+    }
 
-	  cout << current_input_line << "\n";
-	}
-    }
   input_line_number++;
+
   return status;
 }
 

--- a/src/user-prefs.cc	Wed Jan 18 15:56:40 1995 +0000
+++ b/src/user-prefs.cc	Wed Jan 18 16:35:01 1995 +0000
@@ -77,6 +77,7 @@
   user_pref.pager_binary = 0;
   user_pref.ps1 = 0;
   user_pref.ps2 = 0;
+  user_pref.ps4 = 0;
   user_pref.pwd = 0;
 }
 
@@ -732,6 +733,26 @@
 }
 
 int
+sv_ps4 (void)
+{
+  int status = 0;
+
+  char *s = builtin_string_variable ("PS4");
+  if (s)
+    {
+      delete [] user_pref.ps4;
+      user_pref.ps4 = s;
+    }
+  else
+    {
+      warning ("invalid value specified for PS4");
+      status = -1;
+    }
+
+  return status;
+}
+
+int
 sv_pwd (void)
 {
   int status = 0;

--- a/src/user-prefs.h	Wed Jan 18 15:56:40 1995 +0000
+++ b/src/user-prefs.h	Wed Jan 18 16:35:01 1995 +0000
@@ -61,6 +61,7 @@
   char *pager_binary;
   char *ps1;
   char *ps2;
+  char *ps4;
   char *pwd;
 };
 
@@ -104,6 +105,7 @@
 extern int sv_pager_binary (void);
 extern int sv_ps1 (void);
 extern int sv_ps2 (void);
+extern int sv_ps4 (void);
 extern int sv_pwd (void);
 
 #endif

--- a/src/variables.cc	Wed Jan 18 15:56:40 1995 +0000
+++ b/src/variables.cc	Wed Jan 18 16:35:01 1995 +0000
@@ -1461,6 +1461,9 @@
   DEFVAR ("PS2", SBV_PS2, "> ", 0, 0, 1, sv_ps2,
     "secondary prompt string");
 
+  DEFVAR ("PS4", SBV_PS4, "+ ", 0, 0, 1, sv_ps4,
+    "string printed before echoed input (enabled by --echo-input)");
+
   DEFVAR ("PWD", SBV_PWD, get_working_directory ("initialize_globals"),
 	  0, 1, 1, sv_pwd,
     "current working directory");