Rename small part of multiple files in middle of name using Bash?

Question

I\'d just like to change this

cc211_AMBER_13062012i.II  cc211_GROMOS_13062012i.II
cc211_CHARM_13062012i.II  cc211_OPLS_13062012i.II

to

Answer 1

How about this:

for i in *.II; do mv $i $(echo $i | sed 's/_13/_15/g'); done

This will replace _13 with _15 in all files with extension .II

More information on sed here.