How to set boot flag on USB through the terminal?

linus72 · 04-06-2009, 05:48 PM

What is the command and options.
Thanks.

pixellany · 04-06-2009, 06:02 PM

I think any partitioning program does this---eg fdisk, cfdisk, parted, etc.

linus72 · 04-06-2009, 06:04 PM

Yes, thank you I know that, but what is the terminal way?
I tried "man boot", and several others-nothing.
How would I do it if I was stuck on runlevel 2/3??

syg00 · 04-06-2009, 06:12 PM

Why bother - Linux boot loaders don't use the boot flag.

linus72 · 04-06-2009, 06:19 PM

I'm talking about setting the boot flag on a USB through the terminal-
How is it done?

i92guboj · 04-06-2009, 06:24 PM

As said above, you need to use fdisk (or a similar program). If my memory serves correctly, you need to open the related device and then use the "a" command.

Code:

fdisk /dev/sdd 
# here you will enter the fdisk command line interface
a

And follow whatever instructions appear in your screen. It will surely ask you a partition number.

Anyway, as said above, this is a complete waste of time in most cases. Why do you think that you need to do this? Linux doesn't care at all about the bootable flag, only Windows and dos do as far as I know.

linus72 · 04-06-2009, 06:35 PM

fdisk didn't work-I'm trying to set the bootable flag on a FAT16 USB device. Of course I could use Gparted, but what if I were in a non-X or terminal environment-how can I do it?
Will cfdisk do it?
I tried but couldn't.

Tinkster · 04-06-2009, 06:36 PM

Quote:

Originally Posted by linus72

I'm talking about setting the boot flag on a USB through the terminal-
How is it done?

man sfdisk

Cheers,
Tink

linus72 · 04-06-2009, 06:45 PM

Nope on sfdisk, just tried parted-but it said it couldn't set lop-back flags or something.
I guess Gparted is the only option?

i92guboj · 04-06-2009, 08:09 PM

Quote:

Originally Posted by linus72

fdisk didn't work-I'm trying to set the bootable flag on a FAT16 USB device. Of course I could use Gparted, but what if I were in a non-X or terminal environment-how can I do it?
Will cfdisk do it?
I tried but couldn't.

"Didn't work" tell us absolutely nothing about the problem.

I just tried:

Code:

# LC_ALL=C fdisk /dev/kingston

The number of cylinders for this disk is set to 2031.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
   (e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): p

Disk /dev/kingston: 2063 MB, 2063597568 bytes
32 heads, 62 sectors/track, 2031 cylinders
Units = cylinders of 1984 * 512 = 1015808 bytes
Disk identifier: 0x49e2a461

        Device Boot      Start         End      Blocks   Id  System
/dev/kingston1               1        1012     1003873    e  W95 FAT16 (LBA)

Command (m for help): a
Partition number (1-4): 1

Command (m for help): p

Disk /dev/kingston: 2063 MB, 2063597568 bytes
32 heads, 62 sectors/track, 2031 cylinders
Units = cylinders of 1984 * 512 = 1015808 bytes
Disk identifier: 0x49e2a461

        Device Boot      Start         End      Blocks   Id  System
/dev/kingston1   *           1        1012     1003873    e  W95 FAT16 (LBA)

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

That little asterisk next to kingston1 means that the bootable flag is on.

Quote:

Originally Posted by linus72

Nope on sfdisk, just tried parted-but it said it couldn't set lop-back flags or something.
I guess Gparted is the only option?

That's paradoxic, because gparted is nothing else but a frontend to parted. So, if gparted works, then parted works.

Still we don't know what's the problem you are trying to solve by adding that flag. Are you trying to install Windows on your pendrive or something?

Akuna · 08-10-2010, 12:18 PM

From man parted:

Quote:

set partition flag state
Change the state of the flag on partition to state. Supported flags are: "boot", "root", "swap", "hidden", "raid", "lvm", "lba", and "palo". State should be either "on" or "off".

If for example your usb device was /dev/sdb1 then the syntax would be:

Code:

parted /dev/sdb set 1 boot on