Return list of triplicates
You can use:
sort | uniq -c | awk '$1 == 3'uniq -c gives you a count of occurences in the first column. The awk line filters all lines with has 3 in the first column.
If you want all items occuring 3 or more times write $1 >= 3
You can also pick out just the items names with (if they are just one column with no spaces) with:
sort | uniq -c | awk '$1 >= 3 {print $2}'Ans so on ...