From: "Bart Schaefer" <schaefer@brasslantern.com>
To: Philippe Troin <phil@fifi.org>
Cc: zsh-workers@sunsite.dk
Subject: Re: For loop bug
Date: Mon, 16 Sep 2002 06:25:50 +0000 [thread overview]
Message-ID: <1020916062550.ZM29286@candle.brasslantern.com> (raw)
In-Reply-To: <87elbufs3q.fsf@ceramic.fifi.org>
[Excerpts reordered for clarity.]
On Sep 15, 9:58pm, Philippe Troin wrote:
} Subject: Re: For loop bug
}
} "Bart Schaefer" <schaefer@brasslantern.com> writes:
}
} > On Sep 13, 5:58pm, Philippe Troin wrote:
} > }
} > } % for i in 1 2 3; do { {echo $i; [[ $i == 2 ]] && exit 1; } || break };
} > } > done && echo X
} > } 1
} > } X
} > } %
} >
} > That is not a bug.
}
} But shouldn't it print:
}
} 1
} 2
} X
No, it shouldn't. "for i in 1 2 3 ..."
OK, so the first time around the loop i=1, and zsh echoes 1.
Now we're testing [[ $i == 2 ]], which is [[ 1 == 2 ]] which is false;
hence we have { false && exit 1; } which doesn't call exit but also
doesn't evaluate as true, because the first branch of the && is false.
So the outer expression becomes { { false } || break }; and the loop ends
immediately.
} The echo $i with i set to 2 occurs before the exit and break
} statements.
$i never has a chance to get set to 2.
} > Further, { } is not a subshell, so { [[ 2 == 2 ]] && exit 1; } would most
} > likely produce something like
} >
} > login:
} >
} > which might surprise you even more.
}
} I'm not sure I get this part.
If you call { exit 1 } from an interactive zsh, the shell will exit and
you'll end up back at your login prompt (or your xterm will disappear or
your remote connection will drop or whatever). Expressions in { } are
evaluated in the current shell. If it were ( exit 1 ) with parens, that's
evaluated in a subshell and the interactive shell would keep running.
--
Bart Schaefer Brass Lantern Enterprises
http://www.well.com/user/barts http://www.brasslantern.com
Zsh: http://www.zsh.org | PHPerl Project: http://phperl.sourceforge.net
next prev parent reply other threads:[~2002-09-16 6:26 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-13 18:25 Philippe Troin
2002-09-13 23:31 ` Peter Stephenson
2002-09-14 0:34 ` Bart Schaefer
2002-09-14 0:58 ` Philippe Troin
2002-09-14 4:56 ` Bart Schaefer
2002-09-16 4:58 ` Philippe Troin
2002-09-16 6:25 ` Bart Schaefer [this message]
2002-09-16 18:26 ` Philippe Troin
2002-09-16 20:46 ` Hans Dieter Pearcey
2002-09-17 0:08 ` Philippe Troin
2002-09-14 14:39 ` Peter Stephenson
2002-09-17 10:47 ` Peter Stephenson
2002-09-29 13:20 ` Sven Wischnowsky
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