Re: For loop bug

["Bart Schaefer" <schaefer@xxxxxxxxxxxxxxxx>]

[Excerpts reordered for clarity.]

On Sep 15,  9:58pm, Philippe Troin wrote:
} Subject: Re: For loop bug
}
} "Bart Schaefer" <schaefer@xxxxxxxxxxxxxxxx> 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

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