awk or sed or perl: remove only characters on specific position

Question

I have multiple files to rename

    leng-1494-001
    leng-1464-002
    leng-2414-004
    leng-7894-005
    leng-1323-006

I want to rename it

    ferr-1494-001
    ferr-1464-002
    ferr-2414-004
    ferr-7894-005
    ferr-1323-006

I know how to do for ferr and leng,but how to replace characters from 6 to 10( 1464,7894) with blank line for example,or string like aaaa bbbb cccc using sed? Also awk or perl solution is welcome. Thanks

Answer 1

Using sed:

sed -r 's/(.*[a-zA-Z]{4}\-)([0-9]{4})/\1aaaa/g'

Answer 2

POSIXly:

$ sed -e 's/-[^-]*-/-/' file
    leng-001
    leng-002
    leng-004
    leng-005
    leng-006

Answer 3

I found a solution using perl substring function

echo     leng-1323-006|perl -lpe 'substr($_, 5, 5) = "";'

return correctly

leng-006

I hve removed from position 5 the 5 bad characters include the -