Have a look at Text::Format at CPAN. The following is straight from the documentation

$text = Text::Format->new ( 
        {
            text           =>  [], # all
            columns        =>  72, # format, paragraphs, center
            leftMargin     =>   0, # format, paragraphs, center
            rightMargin    =>   0, # format, paragraphs, center
            firstIndent    =>   4, # format, paragraphs
            bodyIndent     =>   0, # format, paragraphs
            rightFill      =>   0, # format, paragraphs
            rightAlign     =>   0, # format, paragraphs
            justify        =>   0, # format, paragraphs
            extraSpace     =>   0, # format, paragraphs
            abbrevs        =>  {}, # format, paragraphs
            hangingIndent  =>   0, # format, paragraphs
            hangingText    =>  [], # format, paragraphs
            noBreak        =>   0, # format, paragraphs
            noBreakRegex   =>  {}, # format, paragraphs
            tabstop        =>   8, # expand, unexpand,  center
        }
    ); # these are the default values
[download]

Justify is the attribute that you need to look at
justify 0 || 1 || NOTHING
Set justify or retrieve its value. Text is aligned with both margins,
adding extra spaces as necessary to align text with left and right margins. Keep in mind that if either of rightAlign or rightFill are set then justify is ignored, even if both are set in which case they are all ignored.
Hope this helps