I'm trying to sort a file using the Sort command but its not working:

The file contains lines like:

photo1
photo11
photo12
photo13
photo17
photo18
photo19
photo2
photo22
photo23
photo25
photo26
photo27


I'm using the command, sort -k6 Photos so that it start sorting after the string "photo", can someone tell where I'm going wrong??


Question: Open problems/questions in representation theory and around?
Answer: There are many open problems on modular representation theory of finite groups. There is a well-known list of problems of R. Brauer which date to around 1960, about ordinary and modular representations of finite groups. There are other major conjectures ( Broue's Abelian defect group conjecture has already been mentioned in comments). There are Alperin's Weight conjecture, Dade's Projective Conjecture, the Isaacs-Navarro conjecture, and several related conjectures. This is only the tip of the iceberg (and only in one corner of representation theory).