Re: How to handle terminal detection in a daemon calling git?

From: Junio C Hamano <gitster@pobox.com>
Date: May 31, 2012, 06:22 UTC
Message-ID: <7vaa0o98e5.fsf@alter.siamese.dyndns.org>
In-Reply-To: <20120531012908.GD5488@sigill.intra.peff.net>

Jeff King <peff@peff.net> writes:

Show 21 quoted lines

> On Wed, May 30, 2012 at 04:16:47PM -0500, Travis P wrote:
>
>> I've got a script that runs in the background without a terminal.
>> It actually does have STDOUT and STDERR set to a rotating log file.
>> 
>> When it runs:
>>   /bin/sh -c 'cd /to/my/wc; git pull --ff-only'
>> the git command fails (rc 32768).
>> 
>> When it runs
>>  /bin/sh -c 'cd /to/my/wc; git pull --ff-only > /to/a/file 2>&1'
>> 
>> or even
>>  /bin/sh -c 'cd /to/my/wc; git pull --ff-only | cat'
>> 
>> then all is well.  The command succeeds (rc 0, and I see the expected
>> results).
>
> If your stdout and stderr are not a terminal in the first place (you say
> they go to a rotating log file), then that should not be making a
> difference. Are they connected by a pty or something odd?

A more likely failure case is when fd 0, 1 and 2 are _closed_.

I vaguely recall we once saw a failure report for that particular case, and then audited the code several years ago, but I do not offhand know if we have regressed over time.