From: Bart Schaefer <schaefer@brasslantern.com>
To: zsh-users@zsh.org
Subject: Re: curiosity with here document.
Date: Thu, 26 Nov 2015 17:56:25 -0800 [thread overview]
Message-ID: <151126175625.ZM22214@torch.brasslantern.com> (raw)
In-Reply-To: <5657939E.7070106@eastlink.ca>
On Nov 26, 3:19pm, Ray Andrews wrote:
}
} lesson learned.
Except it's the wrong lesson! What you *ought* to learn is, first, that
for purposes of determining the "truth value" (zero or nonzero return
status),
if command1; command2; command3; then ...
is the same as
function three_commands {
command1; command2; command3
}
if three_commands; then ...
And second, that [[ ... ]] is just a command like any other command,
it's not magically connected to "if". Further, ":" is also a command
like any other command.
And third, that a here-document is just the standard input of the
command it follows, so
: <<END
some stuff
END
is (again for purposes of determining truth value) the same as
:
and the colon command is "true" for purposes of if/while/until/etc.,
it has a return status of zero. So what you've written is
if [[ ... ]]; : ; then ...
and colon is true and is the last command before the "then", so the
true branch is taken.
The here-document itself has no true or false interpretation, and the
presence of the here-document is not what is causing "if" to behave
the way it does.
next prev parent reply other threads:[~2015-11-27 1:56 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-26 18:37 Ray Andrews
2015-11-26 19:01 ` ZyX
2015-11-26 19:03 ` ZyX
2015-11-26 23:19 ` Ray Andrews
2015-11-27 1:56 ` Bart Schaefer [this message]
2015-11-27 2:29 ` Ray Andrews
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