gtkwve not displaying waveform

HI.

I written traffic program in fsm.after ran in ghdl simulator gtk wave not dispaying waveform .whats the problem?
commands used :ghdl -a tra.vhd
ghdl -e tra
ghdl -r tra --vcd=tra.vcd=$ --stop-time=100ns
gtkwave tra.vcd
library ieee;
use ieee.std_logic_1164.all;

entity tra is
port(rst,clk : in std_logic;
q : out std_logic_vector(2 downto 0));
end;

architecture fsm of tra is

type state_type is(red,green,yellow);

signal ps,ns1 : state_type;
begin
process(clk,rst)
begin
if(rst = '0')then
ps <= red;
elsif clk'event and clk='1'then
ps <= ns1;
end if;
end process;

process(ps,ns1)
begin
case ps is
when red =>
q <="001";
ns1<= green;
when green =>
q <= "010";
ns1 <= yellow;
when yellow =>

q <= "100";
ns1 <= red;
end case;
end process;
end fsm;

Thanks in advence

Regards
Raghavendra

Thanks..
I done like this on command line ghdl -r tra --vcdgz=ghdl vcd.gz
compilation error unknown option 'vcd.gz',

please guide me how to write run command on command line.

Thanks..i will try..:-


Regards
Raghavendra:-

I created a test bench for tra.vhdl (tra_test.vhdl):

--
-- tra_test.vhdl, test bench for tra.vhdl
--
-- supplies clock and reset
--
--

library ieee;
use ieee.std_logic_1164.all;

entity tra_test is
end;

architecture test of tra_test is

signal q: std_logic_vector (2 downto 0);
signal clk: std_logic;
signal rst: std_logic;

component tra is
port (
rst: in std_logic;
clk: in std_logic;
q: out std_logic_vector (2 downto 0)
);
end component;

begin

RESET: -- negative true reset despite name
process
begin
if rst /= '0' then
rst <= '0';
end if;
wait for 22 ns;
rst <= '1';
wait;
end process;

CLOCK:
process
begin
if clk /= '0' then
clk <= '0';
end if;
wait for 10 ns;
clk <= not clk;
end process;

TRATEST:
component tra
port map (
rst => rst,
clk => clk,
q => q
);
end;

--

Once tra.vhdl (your original vhdl) has been analyzed, analyze tra_test.vhdl:
ghdl -a tra_test.vhdl

Then run it:
ghdl -r tra_test --vcd=tra.vcd --stop-time=110ns

Then run gtkwave
gtkwave tra.vcd tra.sav

The optional save file tra.sav:
[timestart] 0
[size] 1000 600
[pos] 195 2
*-24.992649 9100000 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
@28
clk
@29
q[2:0]
@28
rst
[pattern_trace] 1
[pattern_trace] 0

--

You could also use ghdl's native wave form format:

ghdl -r tra_test --stop-time=110ns --wave=tra_testbench.ghw

and display it with gtkwave:

gtkwave tra_testbench.ghw tra_testbench.sav

where tra_testbench.sav contains:
[timestart] 0
[size] 1000 600
[pos] 195 2
*-24.992649 9100000 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
[treeopen] top.
[treeopen] top.tra_test.
[treeopen] top.tra_test.tratest.
@28
top.tra_test.tratest.clk
top.tra_test.tratest.rst
@29
#{top.tra_test.tratest.q[2:0]} top.tra_test.tratest.q[2] top.tra_test.tratest.q[1] top.tra_test.tratest.q[0]
[pattern_trace] 1
[pattern_trace] 0

--

And you can of course setup your own save files in gtkwave by leaving off tra.sav or tra_testbench.sav on the gtkwave command line.

Thanks Diogratia...i will try