I have a list with hexadecimal lines. For example: 

```
0b 5a 3f 5a 7d d0 5d e6 2b c4 7e 7d c2 c0 e6 9a 
84 bd aa 74 f3 85 da 9d ac b6 e0 b6 62 0f b5 d5
c0 b0 f5 60 02 8b 1c a4 41 7c 53 f2 85 20 a0 d1
...

```

I'm trying to find all the lines with grep, where there is a character that occurs only once in the line.

For example: there is only one time a 'd' in the third line.

I tried this, but it's not working:

```
egrep '^.*([a-f0-9])[^\1]*$'

```