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Post 14652 by Kelam_Magnus on Monday 4th of February 2002 02:08:06 PM
02-04-2002
/dev/zero vs /dev/null
Since yall brought this up, I have a question.
What is the difference between. These two commands
1) cat /dev/null > somefile
2) cat /dev/zero > somefile
3) > somefile
Zeroing out a file.
I know that "dd can be used to create a file of X bytes for testing and to "hold" space in a filesytem and for doing "disk dumps" an d for destroying data on a disk ( not the prescribed method).
I think I know another reason for /dev/zero. That would be to zero out a disk for reuse.
Any insight would be informative.
What is the difference between. These two commands
1) cat /dev/null > somefile
2) cat /dev/zero > somefile
3) > somefile
Zeroing out a file.
I know that "dd can be used to create a file of X bytes for testing and to "hold" space in a filesytem and for doing "disk dumps" an d for destroying data on a disk ( not the prescribed method).
I think I know another reason for /dev/zero. That would be to zero out a disk for reuse.
Any insight would be informative.
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LEARN ABOUT SUSE
fdformat
FDFORMAT(8) Linux Programmer's Manual FDFORMAT(8) NAME
fdformat - Low-level formats a floppy disk SYNOPSIS
fdformat [-n] device DESCRIPTION
fdformat does a low level format on a floppy disk. device is usually one of the following (for floppy devices, the major = 2, and the minor is shown for informational purposes only): /dev/fd0d360 (minor = 4) /dev/fd0h1200 (minor = 8) /dev/fd0D360 (minor = 12) /dev/fd0H360 (minor = 12) /dev/fd0D720 (minor = 16) /dev/fd0H720 (minor = 16) /dev/fd0h360 (minor = 20) /dev/fd0h720 (minor = 24) /dev/fd0H1440 (minor = 28) /dev/fd1d360 (minor = 5) /dev/fd1h1200 (minor = 9) /dev/fd1D360 (minor = 13) /dev/fd1H360 (minor = 13) /dev/fd1D720 (minor = 17) /dev/fd1H720 (minor = 17) /dev/fd1h360 (minor = 21) /dev/fd1h720 (minor = 25) /dev/fd1H1440 (minor = 29) The generic floppy devices, /dev/fd0 and /dev/fd1, will fail to work with fdformat when a non-standard format is being used, or if the for- mat has not been autodetected earlier. In this case, use setfdprm(8) to load the disk parameters. OPTIONS
-n No verify. This option will disable the verification that is performed after the format. SEE ALSO
fd(4), setfdprm(8), mkfs(8), emkfs(8) AUTHOR
Werner Almesberger (almesber@nessie.cs.id.ethz.ch) AVAILABILITY
The fdformat command is part of the util-linux-ng package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/. Linux 0.99 1 February 1993 FDFORMAT(8)