Error in the manual regarding the '=~' operator

[Guebitz Roland]

Hello,
in the section
https://www.gnu.org/software/bash/manual/bash.html#Conditional-Constructs
you have this example:
[[ $line =~ [[:space:]]*?(a)b ]]
The expression ?() is not part of the Posix ERE. It is part of bash pattern 
matching: https://www.gnu.org/software/bash/manual/bash.html#Pattern-Matching
Consider this example, which will not match:
line="aaab"
echo $line
if [[ $line =~ '?(a)b' ]]; then
echo Match
echo ${BASH_REMATCH[0]}
echo ${BASH_REMATCH[1]}
else
echo No match
fi
Kind regards,
Roland



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