With field seperator as ".", third column in that case will be "commands... commands... commands...".
Anyway, you can sort any column with sort
~$ sort -t "." -n -k2 infile.txt
~$ sort -t "<field-seperator>" -n -k<column-no> <input-file>
Where, -n option is used for numeric sorting, which in your case, with FS as ".", column 2, not third.
For more details, refer: man sort