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Re: We should Axe /contrib/start-scripts

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Greg Stark <gsstark(at)mit(dot)edu>
Cc: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Chander Ganesan <chander(at)otg-nc(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: We should Axe /contrib/start-scripts
Date: 2009-08-27 00:01:17
Message-ID: 24673.1251331277@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Greg Stark <gsstark(at)mit(dot)edu> writes:
> On Thu, Aug 27, 2009 at 12:32 AM, Tom Lane<tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Attached is a simple patch that uses the environment-variable approach.

> So with this change you would have the startup script not remove the
> lock file?

Huh?  The startup script shouldn't *ever* remove the lock file.
That's been true all along, and this doesn't change it.

> This could still fail if the startup script runs some other commands
> with & to background them and those commands happen to land with the
> pid of postgres? Or the startup script runs pg_ctl within a ( )
> subshell?

Yup, and that's been true all along too.  This patch makes it possible
to write a safe initscript that uses pg_ctl --- it doesn't make it
impossible to write an unsafe one.

In practice, the situations where people would need to write unsafe
constructs have been largely eliminated anyway.  Before we had a builtin
syslogger process, people often wanted to do something like

	su - postgres -c "postmaster | logrotate"

which is quite unsafe because there's probably an intermediate shell
process.  No need for that anymore.  But notice this is just as unsafe
whether you use pg_ctl or postmaster directly ...

			regards, tom lane

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