-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Tue, Mar 07, 2017 at 10:26:25AM +0200, Teemu Likonen wrote: > David Christensen [2017-03-06 21:05:31-08] wrote: > > > # dd if=/dev/sda | gzip > myimage.img > > What's the point of using dd? > > gzip </dev/sda >myimage.img > > I don't know about you but many people seem to think that dd is some > kind of special tool [...]
> To copy a device file: > > cat /dev/foo >image.img > > To write to a device: > > cp image.img /dev/foo > sync Yep. That's when you want to copy all the source, whereas dd comes in handy whin you know how much to copy. So this idiom makes sense dd if=/dev/zero of=lotsofnull bs=1024 count=1024 # copy 1M of zeros whereas (kids, *don't try this at home) cp /dev/zero of=lotsofnull # try to fill up your hard disk ain't what you're usually looking for ;-P But yes dd is a dinosaur from olden times where block sizes were a thing (although I have seen slight speed differences by varying bs on a fairly modern system, but that might have been some voodoo). regards - -- tomás -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iEYEARECAAYFAli+cLoACgkQBcgs9XrR2kZkTwCeI39NI4d06CtufHonaI2u4Ekd XDEAn2QKG+3SAspnF92iNbMpUNwFifUJ =elCY -----END PGP SIGNATURE-----
