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Re: [Help-bash] What is : good for
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From: |
Eric Blake |
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Subject: |
Re: [Help-bash] What is : good for |
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Date: |
Fri, 19 Feb 2016 15:41:57 -0700 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 |
On 02/19/2016 03:40 PM, Eric Blake wrote:
> On 02/19/2016 03:19 PM, Greg Wooledge wrote:
>> "Performing redirections" is probably for something like this:
>>
>> : >file_i_want_truncated
>>
>> Which of course is equivalent to:
>>
>>> file_i_want_truncated
>
> They are equivalent at the top level, but according to POSIX, they are
> NOT equivalent in a subshell:
Make that command substitution.
>
> $(>file_i_want_truncated) is undefined in POSIX, while $(:
>> file_i_want_truncated) is well-defined.
>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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