Subsetting a font from the command line and turning it into a webfont

This is bigger than I originally thought. To do the whole thing, we need some extra tools and some aren't well packaged for Ubuntu. I'm doing the custom installs in ~/src/ —which you'll probably need to create— rather than installing to the system, if only because that's Good Enough™ to get the job done.

sudo apt-get install fontforge python-scour woff-tools build-essential

git clone http://github.com/behdad/fonttools ~/src/fonttools
ln -s ~/src/fonttools/Tools/pyftsubset ~/bin/subset  # vanity symlink

git clone https://github.com/metaflop/ttf2eot.git ~/src/ttf2eot
cd ~/src/ttf2eot
make
cd -

git clone --recursive https://github.com/google/woff2.git ~/src/woff2
cd ~/src/woff2
make clean all
cd -

The next step is working out what unicode characters it is we need. We're going to build a list of characters in the hex format 0x####. Identifying these is just a case of picking through my .less file for the function I use for Font Awesome, but you could do something similar looking for raw content: "..." groups:

perl -n -e '/\.font-awesome..(\w+)/ && print "0xf$1\n"' less/*.less | tail -n+2 | sort -u

Now we have the list, we can tell FontForge to subset FontAwesome.otf:

~/src/fonttools/Tools/pyftsubset fonts/FontAwesome.otf \
--unicodes-file=<(perl -n -e '/\.font-awesome..(\w+)/ && print "0xf$1\n"' less/sbnew-*.less\
| tail -n+2 | sort -u) --output-file=fonts/fa-subset.otf --no-recommended-glyphs --no-hinting

This creates a new .otf font. We can then recondition that into a set of webfonts:

# generate TTF and SVG
fontforge -lang=pe -script <(echo -e 'Open($1)\nGenerate($1:r + ".ttf")\nGenerate($1:r + "big.svg")') fonts/fa-subset.otf

# Clean up SVG
scour -i fonts/fa-subset.big.svg -o fonts/fa-subset.svg --enable-id-stripping --enable-comment-stripping --shorten-ids

# Create WOFF
sfnt2woff fonts/fa-subset.otf

# Create WOFF2 for most modern browsers
~/src/woff2/woff2_compress fonts/fa-subset.ttf

# Create EOT (eotfast might be better)
~/src/ttf2eot/ttf2eot fonts/fa-subset.ttf > fonts/fa-subset.eot

The result is a much smaller set of fonts. Here's the side-by-side comparison:

-rw-r--r-- 1 oli oli  62K Dec 11  2013 FontAwesome.otf
-rw-rw-r-- 1 oli oli 2.0K Aug 27 15:16 fa-subset.otf

-rwxr-xr-x 1 oli oli  38K Dec 11  2013 fontawesome-webfont.eot
-rw-rw-r-- 1 oli oli 3.1K Aug 27 15:31 fa-subset.eot

-rwxr-xr-x 1 oli oli 198K Dec 11  2013 fontawesome-webfont.svg
-rw-rw-r-- 1 oli oli 4.4K Aug 27 15:37 fa-subset.svg

-rwxr-xr-x 1 oli oli  79K Dec 11  2013 fontawesome-webfont.ttf
-rw-rw-r-- 1 oli oli 2.9K Aug 27 15:22 fa-subset.ttf

-rwxr-xr-x 1 oli oli  44K Dec 11  2013 fontawesome-webfont.woff
-rw-rw-r-- 1 oli oli 1.9K Aug 27 15:25 fa-subset.woff
-rw-rw-r-- 1 oli oli 1.4K Aug 27 16:01 fa-subset.woff2