NAME

dsplit − split/unsplit large files across floppies

SYNOPSIS

data stream | dsplit [ −t title ] [ −b blocksize ] [ −F ] [ −f ] [ floppy-device ]
dsplit [ −t title ] [ −b blocksize ] [ −F ] [ −f ] [ floppy-device ] | data stream
dsplit −v [ floppy-device ]

DESCRIPTION

This utility enables the user to take a data stream and put it onto a named sequence of floppy discs. Typical uses would be to put the output of tar or cpio onto a disc set, if necessary formatting the floppies as required. 

It should appear at the end of a pipeline if it is required to save onto floppies, or at the beginning if it is required to recover from floppies. 

In each case the standard input or standard output should be left connected to a terminal, and the other one attached to a pipeline, enabling the program to determine the intended use from the context. 

The first disc should be loaded into the drive to begin with, and in the archive case is given a title, which may be specified using the −t option, alternatively it is prompted for on the terminal when the program starts. This title and a sequence number is put into the first block of each disc as the program proceeds, for subsequent checking when the archive is read back in. 

As each disc is filled, the program halts and prompts the user to unload the disc and load the next one. 

The −bblocksize option specifies a blocksize to be associated with the data stream. When the data is subsequently recovered, the data will be written to the output in units of this size, which may be written explicitly as a number or as a number followed by b or k to represent blocks (of 512 bytes) or kilobytes (i.e. 1024) bytes respectively. 

In the absence of the −b option, then a blocksize appropriate for the floppy is used (this is quite adequate for tar and cpio).

If the −f option is given, each disc is formatted before starting to write on it. 

The program check-reads the disc in every case to ensure that an existing disc is not about to be destroyed before formatting or writing to the current disc and generates appropriate prompts for confirmation. Such checking may be disabled using the −F option. 

Note that an unformatted disc may cause error messages to be output on the console as the program check-reads the disc to see whether or not it has been formatted. 

If no floppy device name is given, then the standard floppy device, /dev/rfdf1024, is assumed.

On recovery, the program checks that the archive floppies are loaded in the correct order, and also verifies the title. If this is specified using the −t option, then the program proceeds to process the first disc, and if the title matches, will make no comment. Otherwise, or if the title does not match, an appropriate message is generated and the program requests confirmation before proceeding, although this may be suppressed using the −F option. Messages about out-of-sequence or invalid discs cannot be suppressed, however. 

The −bblocksize option specifies a blocksize to be associated with the data stream. When the data is recovered, the data will be written to the output in units of this size, which may be written explicitly as a number or as a number followed by b or k to represent blocks (of 512 bytes) or kilobytes (i.e. 1024) bytes respectively.  If the data was written to the disc with a blocksize specified, and a blocksize specified with this option does not match, this is queried before continuing. 

The sequence number put with the title on each disc includes the current date and time as each disc is processed as a further check, in case the same title is given each time. 

The program may also be invoked with the −v option and no data stream to display the title, sequence number and date and time of a given disc. However this is no substitute for a physical label. 

FILES

/dev/rfdf∗

SEE ALSO

cpio(1), dump(8), tar(1). 

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