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Re: ash-20040127-3: Invalid behavior of negated pipeline
- From: Corinna Vinschen <corinna-cygwin at cygwin dot com>
- To: cygwin at cygwin dot com
- Cc: Dmitry Semyonov <linulin at gmail dot com>
- Date: Tue, 12 Aug 2008 17:40:59 +0200
- Subject: Re: ash-20040127-3: Invalid behavior of negated pipeline
- References: <ddc185be0808120836v7f00219br31952f20089f052@mail.gmail.com>
- Reply-to: cygwin at cygwin dot com
On Aug 12 19:36, Dmitry Semyonov wrote:
> Hello all,
>
> -- begin --
> $ bash -c '! true | false; echo $?'
> 0
>
> $ ash -c '! true | false; echo $?'
> 1
> -- end --
>
> Mostly "if" conditions are affected by this issue.
>
> Quote[1] from the "Shell Command Language" standard: "If the reserved
> word ! does not precede the pipeline, the exit status shall be the
> exit status of the last command specified in the pipeline. Otherwise,
> the exit status shall be the logical NOT of the exit status of the
> last command. That is, if the last command returns zero, the exit
> status shall be 1; if the last command returns greater than zero, the
> exit status shall be zero."
>
> [1] http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_09_02
>
>
> So, in this particular case, ash is not compliant with the standard,
> nor it is compatible with bash or dash (Debian ash derivative).
Use bash as sh. ash is only in the distro to run rebaseall. I won't
release a new version of ash any time soon, if it doesn't explicitely
affect rebase.
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Project Co-Leader cygwin AT cygwin DOT com
Red Hat
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