sfddiff man page
sfddiff — compare two font files
sfddiff [--help] [--ignorehints] [--ignorenames] [--ignoregpos] [--ignoregsub] [--ignorebitmaps] [--exact] [--warn] [--merge outfile] [--usage] [--version] fontfile1 fontfile2
The program sfddiff compares two font files, which may be in any format that fontforge(1) can read. It will notice the following differences:
Characters are present in one font but not in the other.
Characters are present in both fonts but have different sets of outlines or references. The outlines may be compared so that only exact matches are accepted, or so that a fuzzier match is used. Similarly references may need to match exactly, or may be matched after an unlink. This fuzzy comparison is useful when comparing truetype and postscript fonts, or when comparing a font with references to one without.
The PostScript hints or TrueType instructions are different.
The font names (the TrueType 'name' tables) differ.
The kerning (and other 'gpos' information) differs.
The ligatures (and other 'gsub' information) differ.
Any bitmap strikes present in one font but not in the other.
Any bitmap characters present in one strike of one font but not in the equivalent strike of the other.
Any bitmap characters which differ.
Provide a description with a list of the available options.
Suppress the reporting of hint/instruction differences.
Suppress the reporting of kerning (and other 'gpos') differences.
Suppress the reporting of ligature (and other 'gsub') differences.
Suppress the reporting of name string differences.
Suppress the reporting of bitmap differences.
Require outlines to match exactly.
Warn if the outlines/references are slightly different.
- --merge outfile
Store a merged version of the two fonts into the specified output file. The merged data will be based on sfdfile1, any characters present in sfdfile2 but not in sfdfile1 will be added, and the outlines of sfdfile2 will be placed in the background. Finally, for any characters with different outlines or references the background of the character will contain the outlines from sfdfile2 (references will be unlinked into outlines and those outlines also will be added).
Display the usage description.
Display the current version.
The HTML version of the FontForge manual, available online at: http://fontforge.sourceforge.net/.
FontForge used to be called PfaEdit.
FontForge is Copyright © 2000–2014 by George Williams, and is currently maintained by the FontForge development team. See /usr/share/doc/fontforge/AUTHORS for a comprehensive list of contributors.
The sfddiff program is licensed under GPLv3+: GNU GPL version 3 or later (http://gnu.org/licenses/gpl.html) with many parts covered by a BSD license (http://fontforge.org/license.html). Please read the LICENSE file included in the FontForge distribution for details, or see https://github.com/fontforge/fontforge/blob/master/LICENSE.
FontForge is available as a whole under the terms of the [GNU GPL](http://www.gnu.org/copyleft/gpl.html), version 3 or any later version. However, almost all of its parts are available under the "revised BSD license" ([pdf](http://www.law.yi.org/~sfllaw/talks/bsd.pdf)) because FontForge was mostly written by George Williams, using that license.
The Revised BSD License is very permissive, and allows for code to be combined with other code under other licenses.
There are many useful libraries available under copyleft libre licenses, such as the LGPL and GPL, which FontForge started to use in 2012.
For example, Pango and Cairo are available under the LGPL, and gnulib is available under the GPL.
Advanced features added since 2012 are licensed by their individual developers under the GPLv3.
See the FontForge Github Issue Tracker, at https://github.com/fontforge/fontforge/issues/.