Index: cli/cli-decode.c
===================================================================
RCS file: /cvs/src/src/gdb/cli/cli-decode.c,v
retrieving revision 1.118
diff -u -p -r1.118 cli-decode.c
--- cli/cli-decode.c	10 Apr 2013 15:11:12 -0000	1.118
+++ cli/cli-decode.c	17 Apr 2013 08:56:13 -0000
@@ -1556,6 +1556,9 @@ lookup_cmd (const char **line, struct cm
     }
   else
     {
+      if (**line != '\0' && c->type == set_cmd && !isspace (**line))
+        error (_("Argument must be preceded by space."));
+
       /* We've got something.  It may still not be what the caller
          wants (if this command *needs* a subcommand).  */
       while (**line == ' ' || **line == '\t')
Index: ChangeLog
===================================================================
RCS file: /cvs/src/src/gdb/ChangeLog,v
retrieving revision 1.15428
diff -u -p -r1.15428 ChangeLog
--- ChangeLog	17 Apr 2013 01:02:01 -0000	1.15428
+++ ChangeLog	17 Apr 2013 08:13:56 -0000
@@ -1,3 +1,9 @@
+2013-04-17  Muhammad Bilal  <mbilal@codesourcery.com>
+
+	PR gdb/10462
+	* cli/cli-decode.c (lookup_command): Show an error if there is no space 
+	before argument.
+
 2013-04-17  Yao Qi  <yao@codesourcery.com>
 
 	* top.c (print_gdb_configuration): Print configure-time
Index: gdb.base/default.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/default.exp,v
retrieving revision 1.64
diff -u -p -r1.64 default.exp
--- gdb.base/default.exp	15 Apr 2013 18:09:02 -0000	1.64
+++ gdb.base/default.exp	17 Apr 2013 09:04:13 -0000
@@ -847,6 +847,13 @@ gdb_test "whatis" "The history is empty.
 gdb_test "where" "No stack." "where"
 #test x
 gdb_test "x" "Argument required .starting display address.*" "x"
+#test argument must be preceded by space
+foreach x {"history file" "solib-search-path" "data-directory"} {
+    foreach y {"/home/" "." "~/home"} {
+        gdb_test "set $x$y" "Argument must be preceded by space." "check space before argument"
+        gdb_test_no_output "set $x $y" "set $x $y"
+    }
+}
 
 gdb_exit
Index: ChangeLog
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/ChangeLog,v
retrieving revision 1.3628
diff -u -p -r1.3628 ChangeLog
--- ChangeLog	15 Apr 2013 20:37:36 -0000	1.3628
+++ ChangeLog	17 Apr 2013 08:23:11 -0000
@@ -1,3 +1,8 @@
+2013-04-17  Muhammad Bilal  <mbilal@codesourcery.com>
+
+	PR gdb/10462
+	* gdb.base/default.exp: Add test case.
+
 2013-04-15  Siva Chandra Reddy  <sivachandra@google.com>
 
 	Add option to link testcases with Pthreads library when