I have installed Fedora 17 on my external hard drive which already contained Ubuntu 12.04 and I was able to choose between the two distros. Since then my brother has installed Mint 13 and Centos 6.2 on the same hard drive so we had a choice of 4 Linux distros to boot.
After either Mint or Ubuntu were routinely updated I discovered that the boot menu no longer contained an entry for Fedora. Doing 'sudo update-grub' when booted into either Ubuntu or Mint shows that when the grub.cfg file is being created there is an entry for Fedora so I wondered if anyone could suggest why it doesn't appear in the boot menu and what I can do to make it.
If it helps to make the problem clearer, the disc is partitioned like this:
/dev/sda1 = Fedora 17
/dev/sda2 = Linux Swap
/dev/sda4 = Extended
/dev/sda5 = Ubuntu 12.04
/dev/sda6 = Linux Mint 13
/dev/sda7 = Centos 6.2
If anyone can help, I would be very grateful