COMEDI_ERRNO(3)

💖 COMEDI_ERRNO(3) — the Comedi reference, bestie edition 💖

okay so this is a page from the Comedi reference manual, section 3 (that's the library-functions girlies ✨), and today we're talking about comedi_errno. she's short, she's sweet, she's the one you call when everything's on fire and you need to know why. let's get into it 🫶

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🌸 NAME 🌸

comedi_errno — the number of the last Comedilib error. like, the receipt of your most recent oopsie 💀

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✨ SYNOPSIS ✨

#include <comedilib.h>

int comedi_errno(void);

literally that's it. one include, one function, no arguments, no drama. queen behavior 👑

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💅 DESCRIPTION 💅

so here's the vibe: when a Comedilib function fails, it usually hands you back -1 or NULL — which one depends on the return type, bestie, read the signature 🙈. but that's not the tea. the tea is that inside the library there's an internal variable holding the actual error number, and you can pull it out by calling comedi_errno. and then?? you can turn that number into something human-readable using comedi_perror or comedi_strerror. slay.

these functions are lowkey designed to mimic the behavior of the standard C library functions perror, strerror, and errno. and here's the plot twist: sometimes Comedilib functions return an error that was actually generated inside the C library itself — and in that case, the comedi error message is the same as the C library's. so it's giving "we're just echoing what the C library said" and honestly? valid. collaboration. 🤝

the function comedi_errno returns an integer describing the most recent Comedilib error. that integer is exactly what you'd pass as the errnum parameter to comedi_strerror. periodt. ✨

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🎀 AUTHORS 🎀

the icons who made this happen, no cap:

• 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.

six whole authors. the group project that actually got finished. iconic. 👑

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📜 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

bestie, legal moment incoming — read this part, it's not skippable 😭

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.

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and that's the whole page, bestie 🌈 this was Comedi, dated 03/20/2026, living in section 3 as COMEDI_ERRNO(3). go forth, catch your errors, know your errno 💜✨