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Groups > comp.os.linux.misc > #11227
| Newsgroups | comp.os.linux.misc |
|---|---|
| Subject | Re: need bash indirect variable help |
| References | <lmvmr3$oqu$1@dont-email.me> <ln2h7e$s1t$1@dont-email.me> <ln2m0f$1og$1@dont-email.me> |
| From | floyd@apaflo.com (Floyd L. Davidson) |
| Organization | __________ |
| Date | 2014-06-08 14:50 -0800 |
| Message-ID | <87mwdnm2wl.fld@barrow.com> (permalink) |
Todd <Todd@invalid.invalid> wrote:
>On 06/08/2014 01:31 PM, Jerry Peters wrote:
>>
>> In bash:
>> ~$ x=z
>> ~$ a=x
>> ~$ echo ${!a}
>> z
>>
>
>Hi Jerry,
>
>Thank you!
>
>What exactly does the "!" do?
See the bash man page, under the heading of "Parameter
Expansion", where the third paragraph down describes it.
Indirection, or they suggest "indirect expansion", uses
the contents of a variable as a the variable acted on.
It is the equivalent of the also suggested eval command,
which might be prefered just because it will be more
obvious what the eval command is doing while the bang
operator will be easily missed or confused.
--
Floyd L. Davidson http://www.apaflo.com/
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
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need bash indirect variable help Todd <Todd@invalid.invalid> - 2014-06-07 11:49 -0700
Re: need bash indirect variable help William Unruh <unruh@invalid.ca> - 2014-06-07 23:42 +0000
Re: need bash indirect variable help Eric Pozharski <whynot@pozharski.name> - 2014-06-08 12:19 +0300
Re: need bash indirect variable help Eric Pozharski <whynot@pozharski.name> - 2014-06-09 15:07 +0300
Re: need bash indirect variable help Richard Kettlewell <rjk@greenend.org.uk> - 2014-06-08 09:03 +0100
Re: need bash indirect variable help Todd <Todd@invalid.invalid> - 2014-06-08 02:35 -0700
Re: need bash indirect variable help Huibert Bol <huibert.bol@quicknet.nl> - 2014-06-08 10:29 +0200
Re: need bash indirect variable help Todd <Todd@invalid.invalid> - 2014-06-08 02:36 -0700
Re: need bash indirect variable help Jerry Peters <jerry@example.invalid> - 2014-06-08 20:31 +0000
Re: need bash indirect variable help Todd <Todd@invalid.invalid> - 2014-06-08 14:53 -0700
Re: need bash indirect variable help floyd@apaflo.com (Floyd L. Davidson) - 2014-06-08 14:50 -0800
Re: need bash indirect variable help Jerry Peters <jerry@example.invalid> - 2014-06-09 20:44 +0000
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