--- shell.cold	2010-07-25 23:40:06 +0200
+++ shell.c	2013-10-17 16:29:59 +0200
@@ -117,45 +117,47 @@
 
   return (result);
 }
 
 /* Set the environment variables LINES and COLUMNS to lines and cols,
    respectively. */
 void
 sh_set_lines_and_columns (lines, cols)
      int lines, cols;
 {
   char *b;
 
+  if (getenv ("LINES") && getenv ("COLUMNS")) {
 #if defined (HAVE_SETENV)
   b = (char *)xmalloc (INT_STRLEN_BOUND (int) + 1);
   sprintf (b, "%d", lines);
   setenv ("LINES", b, 1);
   xfree (b);
 
   b = (char *)xmalloc (INT_STRLEN_BOUND (int) + 1);
   sprintf (b, "%d", cols);
   setenv ("COLUMNS", b, 1);
   xfree (b);
 #else /* !HAVE_SETENV */
 #  if defined (HAVE_PUTENV)
   b = (char *)xmalloc (INT_STRLEN_BOUND (int) + sizeof ("LINES=") + 1);
   sprintf (b, "LINES=%d", lines);
   putenv (b);
 
   b = (char *)xmalloc (INT_STRLEN_BOUND (int) + sizeof ("COLUMNS=") + 1);
   sprintf (b, "COLUMNS=%d", cols);
   putenv (b);
 #  endif /* HAVE_PUTENV */
 #endif /* !HAVE_SETENV */
+  }
 }
 
 char *
 sh_get_env_value (varname)
      const char *varname;
 {
   return ((char *)getenv (varname));
 }
 
 char *
 sh_get_home_dir ()
 {