------------------------------------------------------------------------
od (octal dump
-----------------------------------------------------------------------

-a named characters
-b octal format 
-c ASCII characters

$ cat > infile
a
b
^?        # here ^? stands for "delete" (ctrl v and then delete; delete char)

$ wc infile
       3       3       6 infile

$ od -b                         #octal dump
0000000   141 012 142 012 177 012          #0000000 byte offset          
0000006                                    #0000006 byte offset

$ od -a -b i-c infile
0000000    a  nl   b  nl del  nl         #named characters (-a)                              
          141 012 142 012 177 012        #octal format     (-b)                        
           a  \n   b  \n 177  \n         #ASCII character  (-c)

# try "od -a -b -c infile"