devio(1)

devio -- write/read data to/from removable media

Synopsis

   devio -[I|O] pathname [-p -v -h 'header key (50 bytes)'] [-G file]
   	[-M message] [-b]

Description

The devio command is used for writing/reading data to/from removable media (for example, floppies or tapes).

In output mode (-O), it reads its stdin and writes the data to the device named by pathname.

In input mode (-I), it reads the device pathname (which must contain the output of a previous devio -O command) and writes the data to its stdout.

If the data will not fit on a single volume, devio prompts the user for a new volume and waits for a response before continuing.

Command options

-p: By default, devio will print a prompt for the first volume and wait for a response before beginning. With the -p option, this first prompt is skipped. (Subsequent volumes will be prompted for if necessary.)
-v: The -v option causes devio to operate in verbose mode. A '.' is printed for every 4096 bytes, and some totals information at the end. All verbose output is to stderr.
-h: The argument to the -h option is an arbitrary string (use quoting if necessary to prevent the shell from interpreting any of the string) which devio uses as a label for each of the volumes it processes. If the -h option is used in output mode (-O), then the same argument must be provided to -h when reading the data back in input mode (-I). Applications that invoke devio can use the -h option to ascertain that the volume inserted by the user does indeed contain the expected data.
-G file: This option is intended for use by front-end or application programs that invoke devio. If you're running devio at the shell level, you probably won't need this option. The -G option allows a program to specify file as the interface through which devio writes the prompts to the user's input. By default, /dev/tty is the interface. However, in some situations (such as graphics application environments), /dev/tty is not available. Therefore, an alternative interface, such as a pseudo-tty, may be needed.
-M message: Define a message to use when switching media. You can use this option to define the message printed when you reach the end of the medium. One %d can be placed in message to print the sequence number of the next medium needed to continue. message may contain supplementary code set characters.
-b: Batch mode. The -b option is typically used when invoking devio from a batch or at job. It prevents all prompting from occurring. If the data to be processed needs more than one volume, devio will fail rather than prompt for the next volume.

Although the primary intent is for the pathname argument to be a device, it may also be a regular file. If so, the data will simply be written to (read from) the file, with no prompting for subsequent volumes. (The prompt for the first volume is still done if the -p option is not used.)

Examples

The cpio command already has this media-spanning-prompting capability built into it, making it unnecessary to pipe it through devio. But if there is any other processing you want to do to the cpio output before putting it on the media (for example, compression or encryption), devio may be necessary. We will use compression as an example:

find . -print | cpio -oc | compress | devio -O /dev/rdsk/f0t -vp -h "compressed cpio archive"

This will create a cpio archive of everything in the current directory, compress it, and write it to the floppy driver, prompting for new floppies as needed.

To restore the archive:
devio -I /dev/rdsk/f0t -pv -h "compressed cpio archive" | zcat | cpio -idum

References

cpio(1)