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Re: ARGV[@] Not Always Populated
From: |
Chet Ramey |
Subject: |
Re: ARGV[@] Not Always Populated |
Date: |
Wed, 2 Oct 2019 09:10:12 -0400 |
User-agent: |
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 |
On 10/1/19 6:33 PM, Adam Danischewski wrote:
> If you don't access the ARGV array before you drop into a function, ARGV is
> not populated.
> [...]
> If you uncomment the echo at the top of the script then the printing is as
> expected.
> I realize the Bash Documentation states:
> BASH_ARGV
> An array variable containing all of the parameters in the
> current bash
> execution call stack. The final parameter of the last
> subroutine call
> is at the top of the stack; the first parameter of the
> initial call is
> at the bottom. When a subroutine is executed, the parameters
> supplied
> are pushed onto BASH_ARGV. The shell sets BASH_ARGV only
> when in ex‐
> tended debugging mode (see the description of the extdebug
> option to
> the shopt builtin below). Setting extdebug after the shell
> has started
> to execute a script, or
> *referencing this variable when extdebug is not set, may
> result in inconsistent values.*
By default, the array is lazily populated: if you reference BASH_ARGV, and
it hasn't been set up, it will be initialized using the current positional
parameters.
> Many people are using BASH_ARGV:
> e.g.
> https://stackoverflow.com/questions/2740906/how-to-access-command-line-arguments-of-the-caller-inside-a-function
> If it's not too much trouble I think a lot of people would be glad if you
> could make this work in a standardized way.
Doesn't that suggest that the best way to use it in a `standardized' way is
to run `shopt -s extdebug' at the script's top level, before trying to
reference BASH_ARGV?
--
``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/