---
name: "multibuf"
section: "1"
platform: "linux"
package: "kbackup-multibuf"
version: "1.2.11-10"
release: "Debian 3.0 (Woody)"
platforms: ["linux"]
url: "https://new.carta.tech/multibuf"
---

# multibuf(1)

manage multiple volume archives

## NAME

multibuf - manage multiple volume archives

## SYNOPSIS

**multibuf** \[options\] filename

## DESCRIPTION

**multibuf**  is a tape archive manager which provides the capability of extending a single logical archive over multiple physical media volumes.\
 **multibuf** is part of the **KBackup** package. See the documentation of **KBackup** for more information and the conditions of use.

## OPTIONS

- *-r, --read*

  Set read mode. The archive is read from the device named in filename and written to stdout.

- *-w, --write (default)*

  Set write mode. The archive is read from stdin and written to the device named in filename.

- *-v, --verbose*

  Enable verbose progress reporting.

- *-m, --multibuf buffers*

  This enables real double-buffering using shared memory (Linux only) which can be used to keep a tape drive streaming continuously. The parameter is the number of shared buffers to use (at least 2).

- *-b, --blocksize byte\_count (default = 1024)*

  This sets the minimal size of the data blocks used for  the single write/read calls. Normally you should not change this.

- *-n, --nblocks block\_count (default = 100, minimum = 5)*

  Use this option to change the size of the buffers used by multibuf.

- *-c, --command shell-command*

  Set command1, which is executed at end of medium. The default is "dialog --title  with next volume? This command is expected to exit with a status of 0 to indicate that a retry should be performed.

- *-C, --command2 shell-command*

  Set command2, which is executed at beginning of medium. The default is "mt rewind \</dev/tty \>/dev/tty". The exit status of this command is not checked.

- *-R, --retry-command shell-command*

  Set command to execute when finding  wrong sequence number. The default is "dialog --title "KBackup's MultiBuf" --yesno "Detected wrong sequence number.  Retry?" 6 50 \</dev/tty \>/dev/tty". This command is expected to exit with a status of 0 to indicate that a retry should be performed.

- *-1, --end-only*

  Only execute command at end of media. This option disables command2 processing.

- *-2, --begin-and-end (default)*

  Exeute commands at end and begin of media. This option enables command2 processing.

- *-s, --settings*

  Display settings.

- *-x, --exit*

  Exit after processing options (for testing).

- *-h, --header*

  Add header/sequence information to data. This writes media headers with volume sequencing and block sizing information when writing an archive, or utilizes these headers when reading an archive.

- *-E, --no-endmarker*

  Do not use an endmarker. This disables archive writing of archive endmarkers  when writing an an archive, and disables checking for these endmarkers when reading an archive.

- *-F, --file-endmarker*

  Write endmarker as a file on a mounted medium, or expect such an endmarker when reading from a mounted medium.

- *-D, --disable-filemark-fix*

  For debugging purpose only.

- *-V, --version*

  Print version information to stderr.

## EXIT STATUS

0=success, 1=read error, 2=write error, 3=wrong sequence

## EXAMPLE

You can use **multibuf** without **KBackup**. An example:\
 tar czvf - \| multibuf -w -m 10 /dev/tape\
 This will write a tar file using double buffering and possibly spanning multiple physical volumes.

## BUGS

**multibuf** uses the [system(3)](/system/3.md) function internally. See the **system(**3**)** man page for caveats regarding the use of this function in setuid and setgid programs.

## SEE ALSO

**dialog(**1**)**\
 **kbackup(**1**)**\
 **mt(**1**)**

## AUTHOR

Karsten Ballueder  *Ballueder@usa.net*

## COPYRIGHT

**multibuf** is part of the **KBackup** package and protected by the GNU GENERAL PUBLIC LICENSE, Version 2.