bad -- Command

Maintain list of bad blocks
bad [-acdl] device [ block ... ]

A hard disk or floppy disk  may have bad blocks on it: a ``bad block'' is a
portion of disk that is flawed,  and so cannot reliably be read or written.
It is the unusual disk that is free of bad blocks.

COHERENT  keeps a  list of  bad  blocks so  it can  avoid using  them.  The
command bad maintains this bad-block  list for the given device, which must
be  a  block-special  file.   bad  recognizes  the  following  command-line
options:

a   Add each given block to the bad-block list
c   Clear the bad-block list
d   Delete each given block from the bad-block list
l   List all blocks on the bad-block list

Note that bad  merely adds a block to the  list of bad blocks, or removes a
block from that list.  It does  not deallocate any i-node associated with a
block when  adding it to  the bad-block list.   You should run  the command
icheck with the option -s immediately  after bad to correct the problem, or
run the  command fsck. After  you modify the  list of bad  blocks, you must
reboot your system to force the kernel to use this modified list.

The file system  on device should be unmounted if  possible.  You must have
appropriate permissions for device before you can invoke bad. For many file
systems, only the superuser may use  bad to change the bad-block list.  Use
the command badscan to create a prototype file of bad blocks.

When the  command mkfs creates  a file system,  the prototype specification
may include a list of bad blocks for the new file system.

See Also

badscan,
commands,
icheck,
mkfs

© 2012 by Stephen A. Ness