I've been having a little trouble with a Slack install.
I searched around LQ to see how to go about completely wiping out the hda before I try and install again, and I found a couple different commands for this:

dd if=/dev/zero bs=4k of=/dev/hd?
and
dd if=/dev/zero of=/dev/hd? bs=512 count=1000
and simply
dd if=/dev/zero of=/dev/hd?

I understand the last one well enough, but in the first two, what does the "bs=512/4k and count=1000 do? and do I need to do this to completely erase hda?

I would guess the bs= is setting up for a boot sector?

thanks,
Michael

No, bs= is not for setting up a boot sector. I'm not exactly sure what it does, but for your purposes I'm sure either command will be fine.

I simply did:
dd if=/dev/zero of=/dev/hda

Anyway to check that its all wiped clean, or do I just trust it is?

thanks,
Michael

bs= block size
bs=1024 = bs=1k

bs=512k count=2048 =1MB

This is gonna wipe our your MBR also -restore with fdisk or cfdisk.

I knew it stood for something!

Since I didn't specify a block size, what happened? is there a default? or does this just mean there's more I'll have to do with fdisk?
I'm really getting into new territory with this.

I noticed on a previous install, by accident, that typing "setup" while in fdisk I can specify number of cylinders and blocks and so forth. This is something I'll have to do?

thanks.

*****EDIT******
I specify block size when I'm formating the drives, yes? When I'm doing the install it asks for this with the default of 4096?

The combination that works for me is

dd if=/dev/zero of=/dev/hda bs=512 count=1

Although as this totally wipes the disk, I need to install LILO to the MBR to get Slack to boot from hda.

block size defaults to 1k, but it doesn't really matter as formatting will overwrite it and fdisk will overwrite the MBR.
No need to reset cylinders and heads unless it is wrong -you can get these options under fdisk 'option -x' for advanced setup.
Do use fdisk instead of cfdisk for best results.