eval { bork_bork_bork };
if ( $@ =~ m{ \A Can't \s open \s
              ( .+ ) / ( [^/]+ ) \s }xms )
{
    my ( $missing_dir, $log_filename ) = ( $1, $2 );
    if ( ! -d $missing_dir ) {
        # try to make the directory
    }
}