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Re: pg_ctl failure with older Bourne shells (use ${1:+"$@"})

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: Mike Coleman <mkc(at)stowers-institute(dot)org>,pgsql-bugs(at)postgresql(dot)org, mkc(at)mathdogs(dot)com
Subject: Re: pg_ctl failure with older Bourne shells (use ${1:+"$@"})
Date: 2002-07-19 14:37:56
Message-ID: 12720.1027089476@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-bugs
Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> Yes, I have seen this fix before.  Are people still using shells that
> don't handle "$@" properly?  I guess so or you wouldn't have reported
> it.

I remember having submitted just such a patch a few years ago (for a
different one of our scripts of course) when I was still using HPUX 9.
I'm not sure if later HPUXen have better shells.  Plain /bin/sh on this
platform is ancient.

> We only use "$@" in a few places so I am applying this patch.

Could you check for other scripts where the same thing may have snuck
in?

BTW, O'Reilly's "Unix Power Tools" recommends
	${1+"$@"}
as the most portable replacement for "$@".  Mike's version has :+
which is not the same.  My man page for the Bourne shell says

     ${parameter:+word}
                    If parameter is set and is non-null, substitute word;
                    otherwise substitute nothing.

     ...

     If the colon (:) is omitted from the above expressions, the shell only
     checks whether parameter is set or not.

It looks to me like the book's method is more correct --- it won't mess
up in the case where $1 has been explicitly given as "".

			regards, tom lane

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Subject: Re: pg_ctl failure with older Bourne shells (use ${1:+"$@"})
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