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Re: nounset and $! behavior
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From: |
Chet Ramey |
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Subject: |
Re: nounset and $! behavior |
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Date: |
Mon, 12 Nov 2018 20:12:21 -0500 |
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User-agent: |
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 |
On 11/12/18 6:55 PM, Grisha Levit wrote:
> The following crashes bash:
>
> bash-5.0$ set -u
> bash-5.0$ echo ${!,}
> bash: $!: unbound variable
> bash: !: unbound variable
How does it `crash bash'? There's an extra error message, but it correctly
notes that $! is not set. If the shell is not interactive, it exits.
> Testing if $! is set also doesn't seem to be possible:
>
> bash-5.0$ echo ${!-}
> bash: $!: unbound variable
Yes, this should work.
--
``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/