Now I want to do the same thing except put the regular expression in an environment variable: 

export REX="/--Begin--/ && /--End--/"
echo $REX
/--Begin--/ && /--End--/

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But that's not a regexp; that's an expression.

You can do the interpolation in the shell, so that Perl sees what you intent it to see: 

perl -00 -ne 'print if '$REX file.txt

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Here, $REX is exposed to the shell, which sees the above as: 
perl -00 -ne 'print if /--Begin--/ && /--End--/' file.txt

[download]

In reply to Re: Using a regex saved in an environment variable by JavaFan
in thread Using a regex saved in an environment variable by J0ax88

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