use warnings;
use strict;

my @sentences = (
    "This is  [color]some text[/color].\n",
    "This is a [color]test[/color] oops![/color]\n",
    );

s!\[color\](.*)\[/color\]!\[blue\]$1\[/blue\]!g for @sentences;
s!\[/?color\]!!g for @sentences;
print for @sentences;