---
name: "chio"
section: "1"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["freebsd", "openbsd"]
url: "https://new.carta.tech/chio"
---

# chio(1)

medium changer control utility

## NAME

**chio** – medium changer control utility

## SYNOPSIS

**chio** \[**-f** *changer*\] *command* \[*arg* *...*\]

## DESCRIPTION

The **chio** utility is used to control the operation of medium changers, such as those found in tape and optical disk jukeboxes.

The options are as follows:

- **-f** *changer*

  Use the device *changer* rather than the default device */dev/ch0*.

A medium changer apparatus is made up of *elements*. There are five element types: *picker* (medium transport), *slot* (storage), *portal* (import/export), *drive* (data transfer), and *voltag* (select by volume identifier). The *voltag* pseudo-element type allows the selection of tapes by their volume code, which is typically a barcode on the tape. In this command description, the shorthand ‘ET’ will be used to represent an element type, and ‘EU’ will be used to represent an element unit. For example, to represent the first robotic arm in the changer, the ET would be “picker” and the EU would be “0”.

The following commands are supported:

-

  **exchange** *src-ET* *src-EU* *dst1-ET* *dst1-EU* \[*dst2-ET* *dst2-EU*\] \[**inv1**\] \[**inv2**\] Performs a media unit exchange operation. The media unit in *src-ET*/*src-EU* is moved to *dst1-ET*/*dst1-EU* and the media unit previously in *dst1-ET*/*dst1-EU* is moved to *dst2-ET*/*dst2-EU*. In the case of a simple exchange, *dst2-ET*/*dst2-EU* is omitted and the values *src-ET*/*src-EU* are used in their place. The optional modifiers **inv1** and **inv2** specify whether the media units are to be inverted before insertion into *dst1-ET*/*dst2-EU* and *dst2-ET*/*dst2-EU* respectively.

  Note that not all medium changers support the **exchange** operation; the changer must have multiple free pickers or emulate multiple free pickers with transient storage.

- **getpicker**

  Report which picker unit the changer is currently configured to use.

-

  **move** *from-ET* *from-EU* *to-ET* *to-EU* \[**inv**\] Moves the media unit from *from-ET*/*from-EU* to *to-ET*/*to-EU*. If the optional modifier **inv** is specified, the media unit will be inverted before insertion. If *from-ET* is a drive, **chio** will first attempt to open and perform an MTOFFL operation on the [st(4)](/st/4.md) device corresponding to *from-EU*. By default, the [st(4)](/st/4.md) device /dev/rst*X* is used, where *X* is the *from-EU*. This mapping can be changed by using the [chio.conf(5)](/chio.conf/5.md) file.

- **params**

  Report the number of slots, drives, pickers, and portals in the changer, and which picker unit the changer is currently configured to use.

- **position** *to-ET* *to-EU* \[**inv**\]

  Position the picker in front of the element described by *to-ET*/*to-EU*. If the optional modifier **inv** is specified, the media unit will be inverted before insertion.

  Note that not all changers behave as expected in response to this command.

- **setpicker** *unit*

  Configure the changer to use picker *unit*.

- **status**

  \[**-vVa**\] \[*ET*\] Report the status of all elements in the changer. If *ET* is specified, report the status of all elements of type *ET*.

  - **-v**

    Print the primary volume tag for each loaded medium, if any. The volume tag is printed as “LABEL:SERIAL”.

  - **-V**

    Print the alternate volume tag for each loaded medium, if any.

  - **-a**

    Print all additional information (as in **-vV**).

    The status bits output are defined as follows:

    - FULL

      Element contains a media unit.

    - IMPEXP

      Media was deposited into element by an outside human operator.

    - EXCEPT

      Element is in an abnormal state.

    - ACCESS

      Media in this element is accessible by a picker.

    - EXENAB

      Element supports passing media (exporting) to an outside human operator.

    - INENAB

      Element supports receiving media (importing) from an outside human operator.

## ENVIRONMENT

- CHANGER

  The default changer may be overridden by setting this environmental variable to the desired changer device.

## FILES

- */dev/ch0*

  Default changer device.

- */etc/chio.conf*

  Optional configuration file to set up a non-default mapping between [st(4)](/st/4.md) devices and changer drives.

## EXAMPLES

Move the media in slot 3 (fourth slot) to drive 0 (first drive):

```
# chio move slot 3 drive 0
```

Move the media with volume tag 000007L2 to drive 1 (second drive):

```
# chio move voltag 00007L2 drive 1
```

Configure the changer to use picker 2 (third picker) for operations:

```
# chio setpicker 2
```

## SEE ALSO

[mt(1)](/mt/1.md), [ch(4)](/ch/4.md), [st(4)](/st/4.md), [chio.conf(5)](/chio.conf/5.md)

## HISTORY

A **chio** utility appeared in NetBSD 1.3.

## AUTHORS

The **chio** program and SCSI changer driver were written by Jason R. Thorpe for And Communications.