bugs about grep

[杨华]

Hi :
        I got a file abc :
--------
ACCEPT     all  --  10.1.3.68            0.0.0.0/0
ACCEPT     all  --  10.1.3.39            0.0.0.0/0          MAC 
00:B9:00:00:87:26
ACCEPT     all  --  10.1.3.3             0.0.0.0/0
ACCEPT     all  --  10.123.3             0.0.0.0/0
DROP       all  --  0.0.0.0/0            0.0.0.0/0
--------

And I want to find out the line contain "10.1.3.3" .
When I do :
#cat abc | grep -Fw 10.1.3.3
        ----no result .
#cat abc | grep -F 10.1.3.3 | grep -w 10.1.3.3 
ACCEPT     all  --  10.1.3.3             0.0.0.0/0
        ----give out line3 , right answer

also if I delete the first two line in abc file , the result will be
different . both the two command give out the same right answer. 
#cat abc | grep -Fw 10.1.3.3
ACCEPT     all  --  10.1.3.3             0.0.0.0/0
#cat abc | grep -F 10.1.3.3 | grep -w 10.1.3.3 
ACCEPT     all  --  10.1.3.3             0.0.0.0/0

after many retries , I found if I delete the '9' of '10.1.3.39' in line2
or change "39" to whatever not "3x" , then both command can give the
right answer. 

does that means a bug ?

-----------------
by the way , I have try it on solaris , and find the same problem :
I use "cat abc | /usr/xpg4/bin/grep -Fw 10.1.3.3" also give no answer.
the solaris is "SunOS ns1 5.7 Generic_106541-02 sun4u sparc SUNW,Ultra-250"
-----------------

Regards.
Richard Young.
-- 
杨华 <address@hidden>