问在grep中查找包围字符

EN

grep -Po '\?.*?\?' file

grep -oE '\?[^?]*\?' file

grep -P '\?(?=[^?]*\?)|(?<=\?)[^?]*\K\?' file

$ cat fi
foo ?North America?
Is anyone there?
$ grep -P '\?(?=[^?]*\?)|(?<=\?)[^?]*\K\?' fi
foo **?**North America**?**

perl -i -pe "s/\?(?=[^?]*\?)|(?<=\?)[^?]*\K\?/'/g" file

use warnings;
use strict;
use Term::ANSIColor;

my $bold=color("bold blue");
my $normal=color("reset");
my $str='?North America?
Hi ?aa ? aaa
Hello?
kkk?asad0098? a ?
';
$str =~ s/(\?[A-Za-z0-9]*\?)/$bold$1$normal/g;
print $str;