Re: Using grep to find duplicate characters in a word in bash

[Bob Proulx]

LHUHCD wrote:
> Is there a regular expression that can find duplicate characters in a word?  

Normally I love these types of problems and would jump right in.  But
this one has two problems.  One is that it was sent to bug-bash which
is a mailing list for discussion about bugs and features in the bash
shell and your question is off-topic since it has nothing to do with
bash.  A better place to have asked your question would be
help-gnu-utils which is a generic discussion list for all of the gnu
utilities which would include grep.

Secondly this sounds very suspiciously like a homework assignment.  :-)

Bob

> For example, for five-letter words, we would use..... 
>      grep "^.....$" 
> .....to find any five character word
>  
> How can we, at least, find five-letter words with duplicate letters in the
> word using grep in bash?
> 
> ample - no
> apple - yes
> pills - yes
> civic - no (two pairs of duplicates)
> alana - no (includes "triplicate")
> 
> At the very least, I am looking for a grep that finds words with at least a
> duplicate letter inside the word.
> 
> Thanks!
> 
> 
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