---
name: "comedi_command"
section: "3"
platform: "linux"
package: "libcomedi-dev"
version: "0.11.0+5-1.3+b1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/comedi_command"
---

# comedi\_command(3)

start streaming input/output

## NAME

comedi\_command - start streaming input/output

## SYNOPSIS

```
#include <comedilib.h>
```

**int comedi\_command(comedi\_t \*** *device***, comedi\_cmd \*** *command***);**

## DESCRIPTION

The function **comedi\_command** starts a streaming input or output. The command structure pointed to by *command* specifies settings for the acquisition. The command must be able to pass **comedi\_command\_test** with a return value of 0, or **comedi\_command** will fail. For input subdevices, sample values are read using the function **read** on the device file descriptor. For output subdevices, sample values are written using the function **write**.

## RETURN VALUE

On success, 0 is returned. On failure, -1 is returned.

## AUTHORS

**David Schleef** \<ds@schleef.org\>

Author.

**Frank Mori Hess** \<fmhess@users.sourceforge.net\>

Author.

**Herman Bruyninckx** \<Herman.Bruyninckx@mech.kuleuven.ac.be\>

Author.

**Bernd Porr** \<tech@linux-usb-daq.co.uk\>

Author.

**Ian Abbott** \<abbotti@mev.co.uk\>

Author.

**Éric Piel** \<piel@delmic.com\>

Author.

## COPYRIGHT

Copyright © 1998-2003 David Schleef\
 Copyright © 2001-2003, 2005, 2008 Frank Mori Hess\
 Copyright © 2002-2003 Herman Bruyninckx\
 Copyright © 2012 Bernd Porr\
 Copyright © 2012 Ian Abbott\
 Copyright © 2012, 2015 Éric Piel\

This document is part of Comedilib. In the context of this document, the term "source code" as defined by the license is interpreted as the XML source.

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, version 2.1 of the License.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.