diff -up gdbm-1.8.3/dbmopen.c.dbmlock gdbm-1.8.3/dbmopen.c
--- gdbm-1.8.3/dbmopen.c.dbmlock	1999-05-19 02:16:05.000000000 +0200
+++ gdbm-1.8.3/dbmopen.c	2011-01-03 16:17:13.847173371 +0100
@@ -35,6 +35,28 @@
 #include "gdbmerrno.h"
 #include "extern.h"
 
+static int
+get_env_bool(env_var, def)
+      const char *env_var;
+      int def;
+{
+  const char *v = getenv(env_var);
+  if (!v)
+    return def;
+
+  if (!strcasecmp(v, "yes") ||
+      !strcasecmp(v, "true") ||
+      !strcasecmp(v, "on"))
+    return 1;
+
+  if (!strcasecmp(v, "no") ||
+      !strcasecmp(v, "false") ||
+      !strcasecmp(v, "off"))
+    return 0;
+
+  return !!atoi(v);
+}
+
 /* Initialize ndbm system.  FILE is a pointer to the file name.  In
    standard dbm, the database is found in files called FILE.pag and
    FILE.dir.  To make gdbm compatable with dbm using the dbminit call,
@@ -62,7 +84,7 @@ dbm_open (file, flags, mode)
   char* dir_file;	    /* Used to construct "file.dir". */
   struct stat dir_stat;	    /* Stat information for "file.dir". */
   gdbm_file_info *temp_dbf;  /* Temporary file pointer storage. */
-
+  int gdbm_mode = 0;
 
   /* Prepare the correct names of "file.pag" and "file.dir". */
   pag_file = (char *) malloc (strlen (file)+5);
@@ -77,26 +99,22 @@ dbm_open (file, flags, mode)
   strcat (pag_file, ".pag");
   strcpy (dir_file, file);
   strcat (dir_file, ".dir");
-  
+
+  if (!get_env_bool("NDBM_LOCK", 1))
+      gdbm_mode |= GDBM_NOLOCK;
 
   /* Call the actual routine, saving the pointer to the file information. */
   flags &= O_RDONLY | O_RDWR | O_CREAT | O_TRUNC;
   if (flags == O_RDONLY)
-    {
-      temp_dbf = gdbm_open (pag_file, 0, GDBM_READER, 0, NULL);
-    }
+    gdbm_mode |= GDBM_READER;
   else if (flags == (O_RDWR | O_CREAT))
-    {
-      temp_dbf = gdbm_open (pag_file, 0, GDBM_WRCREAT, mode, NULL);
-    }
-  else if ( (flags & O_TRUNC) == O_TRUNC)
-    {
-      temp_dbf = gdbm_open (pag_file, 0, GDBM_NEWDB, mode, NULL);
-    }
+    gdbm_mode |= GDBM_WRCREAT;
+  else if ((flags & O_TRUNC) == O_TRUNC)
+    gdbm_mode |= GDBM_NEWDB;
   else
-    {
-      temp_dbf = gdbm_open (pag_file, 0, GDBM_WRITER, 0, NULL);
-    }
+    gdbm_mode |= GDBM_WRITER;
+
+  temp_dbf = gdbm_open (pag_file, 0, gdbm_mode, mode, NULL);
 
   /* Did we successfully open the file? */
   if (temp_dbf == NULL)
diff -up gdbm-1.8.3/gdbm.3.dbmlock gdbm-1.8.3/gdbm.3
--- gdbm-1.8.3/gdbm.3.dbmlock	2011-01-03 15:59:15.684729255 +0100
+++ gdbm-1.8.3/gdbm.3	2011-01-03 16:17:49.957570637 +0100
@@ -543,7 +543,11 @@ you must link in the \fIgdbm_compat\fR l
 .sp
 	gcc -o prog proc.c -lgdbm -lgdbm_compat
 
-.SH BUGS
+.SH "ENVIRONMENT VARIABLES"
+\fINDBM_LOCK\fR - When the NDBM interface is used, the database file
+is locked by default. Locking might degrade performance when used on a
+NFS share. This environment variable can be set to false to tell GDBM
+not to lock the database file.
 
 .SH "SEE ALSO"
 dbm, ndbm