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From: Rusty Bird <rustybird@openmailbox.org>
To: dash@vger.kernel.org
Cc: Jilles Tjoelker <jilles@stack.nl>
Subject: Re: Ignored alias inside for loop
Date: Sun, 26 Jul 2015 16:09:12 +0000	[thread overview]
Message-ID: <55B50628.5090901@openmailbox.org> (raw)
In-Reply-To: <20150726152602.GA4346@stack.nl>

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Hash: SHA512

Hi Jilles,

> Aliases are expanded during parsing, not during execution (like 
> functions are). The for loop is parsed completely before it is
> executed.

Ah, what confused me was that I wrongly remembered it working inside
an if (instead of for) block. But looking again now, only the alias
*definition* was inside.

> Using a function instead of an alias, or using eval will do what
> you want.

Do you mean replacing the line with: eval "alias foobarbaz='echo ok'"
That doesn't seem to work either (in dash or bash).

> Note that some parts of the parse/execute split are not specified
> by POSIX. In particular, ksh93 and the real Bourne shell parse dot
> scripts completely before executing anything, while most other
> shells parse as needed. Example: given the file alias1.sh below:
> 
> alias foobarbaz='echo ok' foobarbaz
> 
> The result is ok when running  dash -c '. ./alias1.sh'  but a
> command not found error message when running  ksh93 -c '.
> ./alias1.sh'.
> 
> Similarly, a string as passed to the -c option or eval or trap
> builtins may or may not be parsed fully before execution.

Interesting, thanks!

Rusty
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  reply	other threads:[~2015-07-26 16:10 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-26  9:23 Rusty Bird
2015-07-26 15:26 ` Jilles Tjoelker
2015-07-26 16:09   ` Rusty Bird [this message]
2015-07-26 18:41     ` Jilles Tjoelker
2015-07-27  8:24     ` Seb

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