Shell Programming and Scripting

Hi guys,
I am trying to identify the number of duplicate entries in a string inputed by the user. Here is a command I use:

Code:

$ user_input="M T T"
$echo "${user_input}" | awk '{for(i=0;i<=NF;i++) print $i }'| sort | uniq -d

The above works fine for string with multiple letters. The problem is that it sees one letter string as duplicate as well:

Code:

$ user_input="M"
$ echo "${user_input}" | awk '{for(i=0;i<=NF;i++) print $i }'| sort | uniq -d
M
$

Is there a way to force command above to print "blank" for one letter string?
or maybe someone knows a better way to address this.
Thanks a lot for any advice -A

Make i=1 in your for loop...

You can also try this...

Code:

echo "${user_input}" | awk '{for(i=1;i<=NF;i++){a[$i]++}}END{for(i in a){if(a[i]>1){print i}}}'

--ahamed

Thanks a lot ! It worked.