Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Wed, 5 Feb 2014 13:13:24 -0600

Hi Freddie,

On 02/05/2014 11:59 AM, [email protected] wrote:
> just posting a note on an issue we have come across in case it is
> helpful to anybody else. We are using Cygwin procServ on Windows to
> start IOCs (Windows 7 / EPICS BASE 3.14.12.2) and, although stdout
> was appearing when we typed commands in the telnet window, stderr was
> not. When the IOC exited, however, the stderr output appeared so it
> seems that stderr was being buffered.

> A "google" on the subject returned some
> references to this sort of behaviour when the Windows runtime does
> not recognize the connection as a "terminal" - running the IOC
> directly in a console windows certainly work OK

I do not see that buffering behaviour when running an IOC in a Cygwin
OpenSSH session either.

The Linux manpage for setvbuf(3) says "The standard error stream stderr
is always unbuffered by default" which is apparently required by both
the C89 and C99 standards. I would be reluctant to add code to the IOC
to turn buffering off when it should never be necessary to do that.

Might this be indicative of a bug in procServ, or would it make sense/be
possible for procServ to fix the Windows bug (rather than having to
change the programs running under it)?

- Andrew
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System