In linux how do I to get the ascii decimal/hex/oct code from a char or a ascii char from a decimal/hex/oct code.

I see from the [gnu sed user manual](http://www.gnu.org/software/sed/manual/sed.html#Escapes) that I can use the \d# \o# \x#
to specify a character but I am not sure how to use that.

If some one has a better way to get the the ` and ' chars through please help

I want to sed with the backtick '`' character and ''' single quote character. 

> 
> sed '/`/p'
> 
> 
> 

these don't work

> 
> sed '/\'/p'  
> 
>  sed '/`/p' 
> 
> 
>