[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: capture stdout and stderr

From: Thomas Danckaert
Subject: Re: capture stdout and stderr
Date: Sun, 27 May 2018 19:26:54 +0200 (CEST)

From: Stefan Israelsson Tampe <address@hidden>
Subject: Re: capture stdout and stderr
Date: Thu, 24 May 2018 15:25:51 +0200

I think that your code whould work but doesn't because string ports are not file ports and system commands pipes out to file ports.

'open-input-pipe' uses 'scm_open_process' that returns only a read-port and a write-port, the write port is then taped the output string in your run-command.
and it works.

ALso when you create a err-port with pipe, you create a file port nad this will be used translated as an error port for the system comand and it all works. However the failing program uses a string port which is not a file port and it does not end up capturing the error output in the system command.

One would wish that guile if the error port is not a file port make a file port, as done with 'pipe' and create a thread that pipes the data from the file port to the non file port and your code would work. Also similarly behavior for read and write ports towards the shell.

the relevant code is in posix.c, scm_open_process

Hi! Thanks for the message. Indeed, that makes sense. In fact I had some vague intuition that some magic would be needed to channel the stderr output into such a string port. I think the manual could be more explicit about that, though? (e.g. in the section on default ports ). Maybe I should propose a patch to the docs, stating that those "with-x-to-port" methods only work on file ports.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]