I'm playing around with Linux distros that will run from a USB memory stick and will finction as a complete OS, as if running from an HDD. One that I tried installed the bootloader to the stick's MBR. I have since formatted the stick, so the OS is gone, but the bootloader is still there pointing to it.

I need to get rid of the MBR bootloader so that when my laptop boots to the USB stick, the syslinux file points it to the right OS. How do I clear the MBR?

You can re-install the MBR onto the USB Stick with syslinux, for a stick connected as /dev/sda the following will reinstall the MBR, adjust the device name to suit your setup.

HTH

Mad.

Erase the MBR using "dd if=/dev/zero of=/dev/sda bs=512 count=1" assuming the USB stick is sda of course

OK, I ran that command to clear the MBR, but it seems that when it did, it also removed all partition s from the memory stick as well. How do I put a partition on there from the command line?

That was a poor decision. Not knowing syslinux, I would have thought the solution offered by madluther would be the best place to start.

What the dd command actually did was also remove the partition table; although the data in the partitions hasn't been touched.
Not only that, it removed the signature bytes on the disk - which means fdisk and cfdisk won't open the disk. These two utilities are the normal way to create partitions.
testdisk probably will do the job although I haven't looked at the code - maybe parted as well.
Probably gparted as well, if you have a GUI available.

oneandoneis2, I suggest you not offer this advice to anyone else.

spiffytech: As syg00 pointed out, the parted rescue feature usually does a good job of recovering primary partitions. How to use the rescue option is explained here: http://www.gnu.org/software/parted/m...ted.html#SEC24

..........

Regarding the “dd” command:

Once upon a time, a salesman locked himself out of his car in Manhattan. A kid walked up and said “Hey mister, I’ll open your car for $10, but I want the money up front.” So the salesman gave him $10 and the kid picked up a brick and broke the side window. “Hey mister, you didn’t ask me how I was going to do it.”

The OP says the drive has been formatted, implying there was no valuable data on the drive, or I wouldn't have recommended the dd method.

I've never had any problems repartitioning a flash drive that's been dd'd in the manner I mentioned. I forget if I used fdisk or cfdisk, but those are the only partitioners I have installed, so I know for a fact that at least one of them works just fine.

Under the cirumstances, as a simple way of clearing the MBR of a blank disk, I believe the dd method is a good one.

YMMV.

Apologies are in order to oneandoneis2.

I just had the opportunity to zero a hard-disk prior to the laptop being returned to the leasing company.
fdisk opened and created partitions even with the zero'd MBR just fine.
Didn't work the last time I tried it, did with this version of Knoppix (3.9 - kernel 2.6.11).

Live and learn.

I'm glad dd got the respect it deserves! It's the coolest command out there!

dd was never the issue - merely it's use.
Given the wide variety of kernel versions out there, my preference is to useThis clears the entire code section of the MBR, but leaves the partition table and signature bytes intact.