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Re: A background ssh can take over the tty from bash?


From: Clark Wang
Subject: Re: A background ssh can take over the tty from bash?
Date: Tue, 13 Jun 2017 10:16:49 +0800

On Tue, Jun 13, 2017 at 2:48 AM, L A Walsh <address@hidden> wrote:

> Clark Wang wrote:
>
>>
>> I've checked the ssh process and it does not catch SIGTTIN and that's why
>> I'm confused.
>>
>>
> ----
>    From what I understand, a background process will automatically
> block when it tries to read from STDIN.  By definition, processes
> become bg-processes by using '&'.  I haven't looked at the
> code, but I'm guessing that the first 'ssh' that you launched
> (*without* the '&') is the process swallowing your input as
> it was declared to be a some sort of master-multiplexer for
> subsequent slave processes, but that's just a guess.  Maybe
> putting the master in background @ launch (using '&') will
> cause it to auto-block(suspend) as you expect?
>

The first ssh (with `-f`) would fork another ssh running as a daemon which
would detach from the current tty. It makes no difference whether to use
`&` or not. Please see my explanation @stackoverflow:
https://stackoverflow.com/questions/44492312/ .

-clark


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