Re: backtick to NOT set variable

From: Laurent Bercot <>
Date: Fri, 20 May 2016 18:51:28 +0200

On 20/05/2016 18:44, Max Ivanov wrote:
> Pretty much yes. Don't set ENV variable to the output value of a prog
> if prog exited with anything but 0 (== that is what I call error, but
> commands in execline make distinction between error codes and "exit
> due to signal", so backtick might need to do it too to be consistent)

  backtick -i doesn't make the distinction; I don't think it's relevant
here. No matter whether the subprocess crashes or just fails, you don't
want to proceed normally with the substitution.

> Whether to unset variable on error or not I have no opinion. If env
> var was present already and backtick is called to overwrite it,
> somebody might prefer it to be left with previous value, but for
> others natural behavior might be to undefine it.

  I'm not sure either. On the one hand, there's already the -D mechanism
if people want to have a default; on the other hand, it's easy to do
"unexport VAR" before the backtick. I'll probably go with what's easiest
to code.

Received on Fri May 20 2016 - 16:51:28 UTC

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