[clug] Software ergonomics

Bryan Kilgallin bryan at netspeed.com.au
Tue Jan 27 10:56:37 MST 2015

Thanks for the explanation, Jason:

> SIOCADDRT is one of many "socket I/O commands" that you can issue in 
> an ioctl() system call.  You can see the whole gory list here:
> http://lxr.free-electrons.com/source/include/uapi/linux/sockios.h#L28

Horrors! So as a user, I just have to get used to staggering gobbledegook.

> The error code is a bit of a hack.  You see, the ioctl() system call 
> can do a huge number of different things depending on what object is 
> attached to the file descriptor you call it on, and what command you 
> issue.  But there are only a fixed number of errno error values.  So 
> they get re-used with different nuance depending on the object that is 
> being operated on.  And the people who wrote the "route" command just 
> expanded the error return code using the generic messages.  It just so 
> happens that the "File exists" error code is what is returned from the 
> ioctl system call for the SIOCADDRT operation if there's an existing 
> route that clashes with the one you're trying to add.

On a public service review panel, I discovered that "High level 
communication skills, oral and in writing"--meant a pleasant telephone 

> On a box with RPM, you could type:

So I installed the RPM Package Manager.

> [jao900 at raijin3 ~]$ rpm -qf `which route`

  But the quoted section resulted in a "file not found" error message.

> URL : http://net-tools.berlios.de/
> So you could head to that URL and see if there's a mailing list.

But that yielded a "Server not found" error message.

> Unless you want to submit a patch to the 'route' source code yourself 
> I doubt that you'd get much traction with the developers.

I don't feel sufficiently competent to try that! So I think then that my 
need is interpretive.

> Even if you do submit a patch, it's anyone's guess whether it will get 
> integrated and make it into a released binary...

I used to hear public servants wail "You can't beat the system."!

> Most people don't type route commands that often, and of those that 
> do, a lot of them know or guess what the error means.

Yes, that was the case for me. But I am curious, and so looked it up. 
Can you suggest any place to look up strange (system) messages?

> Not being rude here, just... pragmatic.

Using Linux feels far from plug-and-play! I get stopped in my tracks on 
encountering technical detail. So different from the Mac I used a year ago!


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