Shell Programming and Scripting

Hi

I have a file with one column. There are a few replicas in this column, that is some lines look exactly the same. I want to know the ones that occur twice.

Inputfile.xml
"AAH.dbEUR"
"ECT.dbEUR"
"AEGN.dbEUR"
"AAH.dbEUR"
"AKZO.dbEUR"
...

Here I would like to be informed that "AAH.dbEUR" is occuring twice.

Thanks

Code:

sort filename|uniq -d

Code:

awk '{ arr[$0]++}
       END{ for (i in arr) { if (arr[i]>1) {print i, arr[i]} } }' file

Or (if I'm not missing something):

Code:

awk 'x[$0]++==1' filename

Thanks alot. Works perfectly!

Wow.... So the output is any line that appears more than once - but only printed once.

Can you explain what's going on here?

awk arrays are associative - they hash aray indexes.
The syntax says: add one to the array element indexed zero.
But, since the ++ is after the arr[] it means evaluate the value of arr[] before you add one.

So - if arr[ $0 ] is one -- meaning it has been seen before - print $0 because it is a duplicate, then add one to arr[ $0 ]. Now: arr[ $0 ] == 2 so we never print it again no matter how many times it appears.