how to use binary operator in bash 4.2

Question

I try to use binary operator to use regexpression power,

   [[ wwwebhost@all =~ "^.+@.+$" ]]

do not work in bash 4.2 and works in bash 3.2

but this works in bash 4.2(drop the double quote):

   [[ wwwebhost@all =~ ^.+@.+$ ]]

can anyone explain this ?

possible duplicate of why quote removal isn't performed between [[ ... ]]? — kev
– kev, Commented Nov 16, 2012 at 12:30

Mark Reed · Accepted Answer · 2012-11-19 22:45:18Z

1

In bash 4 (actually I thought this was added in 3.2, but maybe not) quotation marks on the right side of a =~ or == operator inside [[...]] tell bash to do simple string comparison rather than regular expression matching. You might think this would not be the case with the explicit "hey, do a regular expression match!" operator =~, but it is.

answered Nov 19, 2012 at 22:45

Mark Reed

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