From: Thomas Rast <trast@student.ethz.ch>
To: "W. Trevor King" <wking@tremily.us>
Cc: Git <git@vger.kernel.org>, Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH] Documentation/githooks: Explain pre-rebase parameters
Date: Tue, 19 Feb 2013 14:17:43 +0100 [thread overview]
Message-ID: <878v6ksars.fsf@pctrast.inf.ethz.ch> (raw)
In-Reply-To: <c19c03f51d71a58fa3795f665fe4a4c0461fa58f.1361271116.git.wking@tremily.us> (W. Trevor King's message of "Tue, 19 Feb 2013 06:03:24 -0500")
"W. Trevor King" <wking@tremily.us> writes:
> I'm not 100% convinced about this, because the git-rebase.sh uses:
>
> "$GIT_DIR/hooks/pre-rebase" ${1+"$@"}
>
> I haven't been able to find documentation for the ${1+"$@"} syntax.
> Is it in POSIX? It's not in the Bash manual:
[...]
> In my local tests, it seems equivalent to "$@".
It's definitely in the bash manual and POSIX[1]: it's a special case of
the ${parameter+word} expansion.
${parameter:+word}
Use Alternate Value. If parameter is null or unset, nothing is
substituted, otherwise the expansion of word is substituted.
plus
... bash tests for a parameter that is unset or null. Omitting the
colon results in a test only for a parameter that is unset.
IIRC this particular usage was designed to suppress warnings about unset
variables.
Footnotes:
[1] http://pubs.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html
--
Thomas Rast
trast@{inf,student}.ethz.ch
next prev parent reply other threads:[~2013-02-19 13:18 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-19 11:03 [PATCH] Documentation/githooks: Explain pre-rebase parameters W. Trevor King
2013-02-19 13:17 ` Thomas Rast [this message]
2013-02-19 13:23 ` W. Trevor King
2013-02-19 17:05 ` Junio C Hamano
2013-02-19 19:08 ` Junio C Hamano
2013-02-20 16:36 ` W. Trevor King
2013-02-20 17:23 ` Junio C Hamano
2013-02-23 15:27 ` [PATCH v2] " W. Trevor King
2013-02-23 21:21 ` Junio C Hamano
2013-02-23 21:35 ` W. Trevor King
2013-02-24 8:13 ` Junio C Hamano
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