Re: [PATCH 2/2] CodingGuidelines: Add note forbidding use of 'which' in shell scripts

From: Junio C Hamano <gitster@pobox.com>
Date: Feb 27, 2012, 18:56 UTC
Message-ID: <7vty2c85ql.fsf@alter.siamese.dyndns.org>
In-Reply-To: <1330117921-8257-2-git-send-email-tim.henigan@gmail.com>

Tim Henigan <tim.henigan@gmail.com> writes:

Show 11 quoted lines

> diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
> index a4ffe7c..3505a4b 100644
> --- a/Documentation/CodingGuidelines
> +++ b/Documentation/CodingGuidelines
> @@ -44,6 +44,10 @@ For shell scripts specifically (not exhaustive):
>     properly nests.  It should have been the way Bourne spelled
>     it from day one, but unfortunately isn't.
>  
> + - The use of 'which' is not allowed.  The output of 'which' is not
> +   machine parseable and its exit code is not reliable across
> +   platforms.

It is more helpful to say "If you want to do Z, use X, not Y because Y is broken for such and such reasons", rather than "Never use Y because Y is broken ...".

In this case, Z is "find out if a command is available on user's $PATH", and X is "type", I think.