perl -le '$_="[987]ABC[GHI]XYZ[dfg]"; print "$_" for split/(?!\w+\])|\[|]/,$_'

##</code><code>##

perl -le '$_="[987]ABC[GHI]XYZ[dfg]";print "$_" for grep{$_}split/(?!\w+\])|\[|]/,$_'