From: Tom Lane <tgl@sss.pgh.pa.us>
To: "Tels" <nospam-pg-abuse@bloodgate.com>
cc: =?utf-8?B?IkRhZ2Zpbm4gSWxtYXJpIE1hbm5zw6VrZXIi?= <ilmari@ilmari.org>,
        "Victor Wagner" <vitus@wagner.pp.ru>,
        "pgsql-hackers" <pgsql-hackers@postgresql.org>
Subject: Re: Non-portable shell code in pg_upgrade tap tests
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Comments: In-reply-to "Tels" <nospam-pg-abuse@bloodgate.com>
	message dated "Sat, 21 Jul 2018 18:49:33 -0400"
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Date: Sat, 21 Jul 2018 19:20:08 -0400
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"Tels" <nospam-pg-abuse@bloodgate.com> writes:
> Looking at your new patch, I notice you used "" for quoting, not ''. (Not
> sure which variant Tom used when pushing a patch).
> I'm not a shell expert, but I think '' are safer, as "" still has some
> interpolation from the shell (at least on the systems I use regulary):

We can't do that here because '' would suppress interpolation of the
variable's value, which is sort of the point.

AFAIK, the locution "$foo" is safe regardless of what is in $foo,
as long as only one pass of shell evaluation is involved.  The shell
will treat the value of $foo as one not-further-interpreted command
argument.

			regards, tom lane