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Re: Some Special Array Variables Only Kind Of Initialized


From: Chet Ramey
Subject: Re: Some Special Array Variables Only Kind Of Initialized
Date: Sat, 11 Jan 2014 16:55:44 -0500
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.2.0

On 1/10/14, 6:06 PM, John R. Graham wrote:
> Some of the automagically created special array variables (GROUPS and 
> DIRSTACK for soer; perhaps others) appear to not be fully initialized. Their 
> values don't appear correctly in some corner cases until they've been 
> referenced with parameter expansion (I think that's the triggering criteria, 
> anyway). The following shell dialog illustrates:

Yes. There are a number of dynamic variables whose values are generated
each time they are referenced.  In most cases, they have no values until
the value is generated the first time.

Here's a partial list from bash-4.3:

BASH_COMMAND
BASH_SUBSHELL
RANDOM
SECONDS
LINENO
BASHPID
COMP_WORDBREAKS
DIRSTACK
GROUPS
FUNCNAME

BASH_ARGC
BASH_ARGV
BASH_SOURCE
BASH_LINENO
BASH_CMDS
BASH_ALIASES

Chet
-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU    address@hidden    http://cnswww.cns.cwru.edu/~chet/



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