Plain text justifier for Linux

Question

I'm composing a plain text (.txt) document that has left-and-right justified paragraphs. I manually add spaces, breaking words with hyphens if necessary, until the lines are uniform length. To use an example from my document, a paragraph like this:

These phantasmic balls have some strange properties, some neat, some
interesting, and others just indicative of lazy design. They're almost all
caused by the same design flaw: The game treats them too much like regular
balls.

will end up looking like this:

These phantasmic balls have some  strange properties,
some neat,  some interesting, and others just indica-
tive of lazy design. They're almost all caused by the
same design flaw:  The game treats them too much like
regular balls.

I'm looking for a program that can do this for me. It's okay if the program only adds spaces (without breaking words over lines), but there MUST be some way to control the target width of the paragraph (in # characters). The example above is justified to 53 characters per line, but line width in my actual document varies from 60 to 79.

Bonus points if you can find a text editor with this feature integrated.

OpenOffice and TeX are not what I'm looking for; they just use formatting to change how the text is displayed. Also, nano's Justify command doesn't count because it doesn't actually make the lines uniform width.

Note: I accepted the following answer because it was the one that worked best for me. I found the emacs fill commands the easiest to use among the answers, and I appreciate how it recognizes even non-whitespace indentation (for stuff like # and // comments). However, the other answers all fill their own niches and I recommend others visiting this question to look at them as well.

Answer 1

You can do this in emacs using fill-paragraph or fill-region (fill docs).

You need to pass a numeric prefix argument. The default fill column is 70.

Select the text to fill and do M-3 M-x fill-region.

I set the fill column to 53 for your sample text and got:

These phantasmic balls  have some strange properties,
some   neat,  some   interesting,  and   others  just
indicative of lazy  design. They're almost all caused
by  the same design  flaw: The  game treats  them too
much like regular balls.

Answer 2

you need par

e.g. to get it on ubuntu, do:

sudo aptitude install par

to justify text.txt (at 80 chars), saving in newtext.txt:

par 80j < text.txt > newtext.txt

to use par in vim or gvim:

:set formatprg=par\ 80j

then highlight the text you want to format and use the gq command.

for more information, see man par

Answer 3

Here's a Perl script called paradj that can do full justification and hyphenation.

Here's a diff showing some changes I made to support adding a left margin:

12c12
< my ($indent, $newline);
---
> my ($indent, $margin, $newline);
15a16
>   "margin:i" => \$margin,
21a23
> $margin = 0 if (!$margin);
149a152
>     print " " x $margin;
187a191,193
>   print "--margin=n (or -m=n or -m n)  Add a left margin of n ";
>   print "spaces\n";
>   print "                                (defaults to 0)\n";

This command:

./paradj.pl -h --width=53 --both --indent=0 inputfile

produces output very close to your example (the extra spaces are in different places).

These  phantasmic balls have some strange properties,
some  neat, some interesting, and others just indica-
tive of lazy design. They're almost all caused by the
same  design flaw: The game treats them too much like
regular balls.

Answer 4

fmt is the old-school solution

From the man page:

fmt [-cmnps] [-d chars] [-l num] [-t num] [goal [maximum] | -width | -w width] [file ...]

and

The goal length defaults to 65 and the maximum to 10 more than the goal length. Alterna- tively, a single width parameter can be specified either by prepending a hyphen to it or by using -w. For example, fmt -w 72'',fmt -72'', and ``fmt 72 72'' all produce identical output.