Bug#727708: systemd socket activation protocol rationale

[Ian Jackson <ijackson@chiark.greenend.org.uk>]

Uoti Urpala writes ("Bug#727708: systemd socket activation protocol rationale"):
> On Sat, 2013-12-14 at 21:45 +0000, Ian Jackson wrote:
> > Why do only some of the environment variables start "SD_" ?
> > We have LISTEN_PID and LISTEN_FDS but SD_LISTEN_FDS_START.
> 
> You misread it: there is no environment variable SD_LISTEN_FDS_START.
> The API defines the start value as the constant 3. There is a
> corresponding #define in sd-daemon.h, but it is not communicated at
> runtime.

Oh, yes, I did misread it, thanks.

> > What is the rationale behind the use of the LISTEN_PID variable and
> > the pid check ?  It seems to me that at the very least this might make
> > it hard to wrap up a socket-activated daemon in a shell script.
> 
> To ensure that the environment values are never accidentally inherited
> by any child process.

That much was clear.  The underlying reason for worrying about this
wasn't.

Ian.