BLOCK(1)		USER COMMANDS			BLOCK(1)

SYNOPSIS
	block [-s volume size in kb] <in >out

DESCRIPTION 
	Block is an utility that enables storing compressed tar 
	archives on multiple floppies by dividing its input or
	output into blocks of the size of a floppy and prompting
	for floppy change between the blocks.

	Block automaticly detects the size of the 1.2 and 1.44 
        M floppies. The size used can also be specified 
	explicitly using the -s option.

	To create an archive on multiple floppies redirect tar's
	output to block through a pipe and block's output to the 
	floppy device. Then change floppies as prompted until 
	the program(s) terminate.	

	To extract an archive from multiple floppies redirect 
	block's input to be read from the floppy device and 
	block's output to tar through a pipe. Then change 
	floppies as prompted until the program(s) terminate.

	Note that block assumes the first floppy to be in the
	drive when started and does not prompt for it.

	The same binary can be used for both creating and 
	extracting archives, since block detects whether its 
	standard input or output is associated with a block device.  

	Although block is intented to be used with tar, it's 
	general nature enables also other uses, such as splitting
	a large file on multiple floppies. Also other storage 
	devices than floppies could be used, provided that they
 	are block devices and the block size is explicitly 
	specified.

EXAMPLES
	The following example assumes that you have the device 
	entry of /dev/PS0 corresponding to 1.44 M A drive 
	(major/minor=2/28). Also, it is assumed that your version 
	of tar supports the 'z' flag for using compress for tar 
	output.

	To create a compressed tar archive of /usr/bin on 1.44 M 
	floppies in drive A give the command :

	tar -cz /usr/bin | block >/dev/PS0

	To extract the archive of the previous example give the 
	command :

	block </dev/PS0 | tar -xz

NOTES
	The floppy device default names and device numbers are 
	listed here for convenience (for Linux 0.96a).

	drive	size 	device name	device major/minor #
	----------------------------------------------------
	A	1.2 M	/dev/at0	2/8
	B       1.2 M	/dev/at1	2/9
	A	1.44M	/dev/PS0	2/28
	B	1.44M	/dev/PS1	2/29

	mknod can be used to create the device special files.

BUGS AND CAVEATS
	The disk buffer size of the program is currently static 
	and therefore the I/O efficency is not the optimum. In 
	practice the loss is minimal, however.

	If the size of the data to be written is a multiple of the 
	floppy size, block prompts for the last floppy in vain, 
	since there is no actual data left to write. 

------------------------------------------------------------------------------
Block 1.0 was written for Linux by J.Leppajarvi.
Comments and bug fixes are welcome (jml@stekt.oulu.fi) 
Public domain. No rights reserved.
This program and the related documentation have no warranty of any kind.
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