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Re: [doc] missing doc about :+ vs + expansion
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From: |
Chet Ramey |
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Subject: |
Re: [doc] missing doc about :+ vs + expansion |
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Date: |
Mon, 25 Mar 2019 09:04:47 -0400 |
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User-agent: |
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.6.0 |
On 3/25/19 6:19 AM, Christophe Lyon wrote:
> Hi,
>
> I think I've noticed a bit of explanation missing in the documentation
> about parameter expansion.
>
> bash supports :+ and + expansion, but 'man bash' describes the former only.
> This is also true for the similar expansions (:-, :=, :?)
"When not performing substring expansion, using the forms documented
below (e.g., :-), bash tests for a parameter that is unset or null.
Omitting the colon results in a test only for a parameter that is
unset."
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU chet@case.edu http://tiswww.cwru.edu/~chet/