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Re: initialisation bash variables

From: Stephane CHAZELAS
Subject: Re: initialisation bash variables
Date: Wed, 28 Mar 2012 18:25:53 -0000
User-agent: slrn/pre1.0.0-18 (Linux)

2011-08-15, 17:15(+02), Francky Leyn:
> Hello,
> if you have a variable, say VAR,
> and you don't assign it a value,
> and afterwards you test it,
> what is the value of $VAR then?
> random, or an empty string?

Upon startup, the shell makes one shell variable per environment
variable whose name is compatible with shell variable names.

So for instance, if bash receives "VAR=foo" in its environemt,
$VAR will expand to foo. If it's passed "1=bar", $1 will not be
affected, and it's the same for a few special variables of the

If passed "A+B=C" or "=D" for instance, that obviously won't be
mapped to shell variables. Some shells do discard variables from
the environment that can't be mapped to shell variables. That's
not the case of bash.


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