Thank you all who answered my question. Here is my conculsion. Just FYI.

> >>Is there any tools under Unix to show files similar to dos debug? I mean
> >>the output looks like the following: so that I can see both the hex code
> >>and the ascii codes:
> >>
> >In terms of "always available" there's "od -cx".

Sample output:

0000000   #   !   /   u   s   r   /   b   i   n   /   s   h  \n   #  \t
            2321    2f75    7372    2f62    696e    2f73    680a    2309
0000020   C   o   p   y   r   i   g   h   t       (   c   )       1   9
            436f    7079    7269    6768    7420    2863    2920    3139

BTW, od -cx1 doesn't work

> >With GNU od
> >(at the very least; I'm not certain how GNU-specific the "z"
> >format is) you can also use "od -tx1z" to better match your
> >sample format.

od: invalid character `z' in type string `x1z'

od -tx1 /bin/true
0000000 23 21 2f 75 73 72 2f 62 69 6e 2f 73 68 0a 23 09
0000020 43 6f 70 79 72 69 67 68 74 20 28 63 29 20 31 39

od -tx1 -c

Sample output:

0000000 23 21 2f 75 73 72 2f 62 69 6e 2f 73 68 0a 23 09
          #   !   /   u   s   r   /   b   i   n   /   s   h  \n   #  \t
0000020 43 6f 70 79 72 69 67 68 74 20 28 63 29 20 31 39
          C   o   p   y   r   i   g   h   t       (   c   )       1   9

This is the best result I can get.

> >There are also a few "hexdump" programs to be
> >found in the comp.sources.* archives.
> >
> >               --Ken Pizzini
>
> Or, if you're an emacs user, did you try
>
>     M-x hexl-mode ?
>
> On the other hand, the format is a bit different but then you can also edit
> the file...
>
>                                    Jens

I settle down with this one. Thanks!