Q: missing operation system

Thanks alot for your answer. Can you please tell me how to do it in bootcamp?

iMac (27-inch, Late 2012) 3,2 GHz Intel Core i5.

It does not have optical drive.

Last login: Thu Aug 25 20:12:30 on console

iMac-alexander:~ alexanderbagirian$ diskutil list

/dev/disk0 (internal, physical):

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:      GUID_partition_scheme                        *1.0 TB     disk0

   1:                        EFI EFI                     209.7 MB   disk0s1

   2:                  Apple_HFS Macintosh HD            798.3 GB   disk0s2

   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3

   4:       Microsoft Basic Data                         201.0 GB   disk0s4

iMac-alexander:~ alexanderbagirian$ diskutil cs list

No CoreStorage logical volume groups found

iMac-alexander:~ alexanderbagirian$ sudo gpt -vv r- show /dev/disk0

Password:

gpt: unknown command: r-

iMac-alexander:~ alexanderbagirian$ sudo gpt -vv r- show /dev/disk0

gpt: unknown command: r-

iMac-alexander:~ alexanderbagirian$ sudo fdisk /dev/disk0sudo dd if=/dev/rdisk0s4 count=1 2>/dev/null | hexdump -C

iMac-alexander:~ alexanderbagirian$

After updating to OS X Capitan, the windows window disapeared. So i looked throug the internet and did this (picture)

I don't know if I did it correclty. But this is what I got!!!!