[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: aliasing "sed" to "sed --posix"
From: |
Bruce Korb |
Subject: |
Re: aliasing "sed" to "sed --posix" |
Date: |
Mon, 06 Aug 2007 07:53:26 -0700 |
User-agent: |
Thunderbird 1.5.0.12 (X11/20060911) |
Bruno Haible wrote:
> Bruce Korb wrote:
>> Aliases are turned off.
>> Below is an experiment. Invoke with and without an argument. The results
>> look like this:
>
> Your experiment uses the 'exit' command to test whether aliases are supported.
> However, 'exit' is a shell built-in. Whereas 'sed' is not and will likely
> never be a shell built-in. Can you retry your experiment with a non-built-in?
>
> In gnulib-tool line 468 you see that the usual way to override built-ins in
> bash is to define them as a function, because 'alias' does not work for them.
Hi Bruno,
Well, I knew ahead of writing the script that unless the shopt
expand_aliases were turned on that they would not work. I had
stumbled into this before. I experimented with aliasing "exit"
because it would have a dramatic effect on the execution flow. :)
Sure enough, if I aliased "exit" to the echo, the echo fired
and I had demonstrated my point: if you want to ensure that
"sed" is run with "--posix", then either ensure that aliases
are expanded within the script, or else use a function. This
is true whether you are aliasing sed or, apparently, exit.
Cheers - Bruce