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mf - Man Page

Metafont, a language for font and logo design


mf [options] [commands]


Metafont reads the program in the specified files and outputs font rasters (in gf format) and font metrics (in tfm format).  The Metafont language is described in The Metafontbook.

Like T E X, Metafont is normally used with a large body of precompiled macros, and font generation in particular requires the support of several macro files.  This version of Metafont looks at its command line to see what name it was called under.  Both inimf and virmf are symlinks to the mf executable.  When called as inimf (or when the -ini option is given) it can be used to precompile macros into a .base file.  When called as virmf it will use the plain base.  When called under any other name, Metafont will use that name as the name of the base to use.  For example, when called as mf the mf base is used, which is identical to the plain base.  Other bases than plain are rarely used.

The commands given on the command line to the Metafont program are passed to it as the first input line.  (But it is often easier to type extended arguments as the first input line, since UNIX shells tend to gobble up or misinterpret Metafont's favorite symbols, like semicolons, unless you quote them.)  As described in The Metafontbook, that first line should begin with a filename, a \controlsequence, or a &basename.

The normal usage is to say

mf  '\mode=<printengine>; [mag=magstep(n);]' input  font

to start processing font.mf. The single quotes are the best way of keeping the Unix shell from misinterpreting the semicolons and from removing the \ character, which is needed here to keep Metafont from thinking that you want to produce a font called mode. (Or you can just say mf and give the other stuff on the next line, without quotes.)  Other control sequences, such as batchmode (for silent operation) can also appear. The name font will be the “jobname”, and is used in forming output file names. If Metafont doesn't get a file name in the first line, the jobname is mfput. The default extension, .mf, can be overridden by specifying an extension explicitly.

A log of error messages goes into the file jobname.log. The output files are jobname.tfm and jobname.<number>gf, where <number> depends on the resolution and magnification of the font.  The mode in this example is shown generically as <printengine>, a symbolic term for which the name of an actual device or, most commonly, the name localfont (see below) must be substituted.  If the mode is not specified or is not valid for your site, Metafont will default to proof mode which produces large character images for use in font design and refinement.  Proof mode can be recognized by the suffix .2602gf after the jobname.  Examples of proof mode output can be found in Computer Modern Typefaces (Volume E of Computers and Typesetting). The system of magsteps is identical to the system used by T E X, with values generally in the range 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0. A listing of gf numbers for 118-dpi, 240-dpi and 300-dpi fonts is shown below.

MAGSTEP118 dpi240 dpi300 dpi

Magnification can also be specified not as a magstep but as an arbitrary value, such as 1.315, to create special character sizes.

Before font production can begin, it is necessary to set up the appropriate base files.  The minimum set of components for font production for a given print-engine is the plain.mf macro file and the local mode_def file.  The macros in plain.mf can be studied in an appendix to the Metafontbook; they were developed by Donald E. Knuth, and this file should never be altered except when it is officially upgraded. Each mode_def specification helps adapt fonts to a particular print-engine. There is a regular discussion of mode_defs in TUGboat, the journal of the T E X Users Group. The local ones in use on this computer should be in modes.mf.

The e response to Metafont's error-recovery mode invokes the system default editor at the erroneous line of the source file. There is an environment variable, MFEDIT, that overrides the default editor. It should contain a string with "%s" indicating where the filename goes and "%d" indicating where the decimal linenumber (if any) goes. For example, an MFEDIT string for the vi editor can be set with the csh command

setenv MFEDIT "vi +%d %s"

A convenient file in the library is null.mf, containing nothing. When mf can't find the file it thinks you want to input, it keeps asking you for another file name; responding `null' gets you out of the loop if you don't want to input anything.

Online Graphics Output

Metafont can use most modern displays, so you can see its output without printing.  Chapter 23 of The Metafontbook describes what you can do.  This implementation of Metafont uses environment variables to determine which display device you want to use. First it looks for a variable MFTERM, and then for TERM. If it can't find either, you get no online output.  Otherwise, the value of the variable determines the device to use: hp2627, sun (for old SunView), tek, uniterm (for an Atari ST Tek 4014 emulator), xterm (for either X10 or X11). Some of these devices may not be supported in all Metafont executables; the choice is made at compilation time.

On some systems, there are two Metafont binaries, mf and mf-nowin. On those systems the mf binary supports graphics, while the mf-nowin binary does not.  The mf-nowin binary is used by scripts like mktexpk where graphics support is a nuisance rather than something helpful.


This version of Metafont understands the following command line options.

-base base

Use base as the name of the base to be used, instead of the name by which Metafont was called or a %& line.

-cnf-line string

Parse string as a texmf.cnf configuration line.  See the Kpathsea manual.


Print error messages in the form file:line:error which is similar to the way many compilers format them.


Disable printing error messages in the file:line:error style.


This is the old name of the -file-line-error option.


Exit with an error code when an error is encountered during processing.


Print help message and exit.


Be inimf, for dumping bases; this is implicitly true if the program is called as inimf.

-interaction mode

Sets the interaction mode.  The mode can be one of batchmode, nonstopmode, scrollmode, and errorstopmode. The meaning of these modes is the same as that of the corresponding commands.

-jobname name

Use name for the job name, instead of deriving it from the name of the input file.

-kpathsea-debug bitmask

Sets path searching debugging flags according to the bitmask.  See the Kpathsea manual for details.

-maketex fmt

Enable mktexfmt, where fmt must be mf.

-no-maketex fmt

Disable mktexfmt, where fmt must be mf.

-output-directory directory

Write output files in directory instead of the current directory.  Look up input files in directory first, the along the normal search path.


If the first line of the main input file begins with %& parse it to look for a dump name or a -translate-file option.


Disable parsing of the first line of the main input file.

-progname name

Pretend to be program name. This affects both the format used and the search paths.


Enable the filename recorder.  This leaves a trace of the files opened for input and output in a file with extension .fls.

-translate-file tcxname

Use the tcxname translation table.


Print version information and exit.


See the Kpathsearch library documentation (the `Path specifications' node) for the details of how the environment variables are use when searching.  The kpsewhich utility can be used to query the values of the variables.

If the environment variable TEXMFOUTPUT is set, Metafont attempts to put its output files in it, if they cannot be put in the current directory.  Again, see tex(1).


Search path for input files.


Command template for switching to editor.


Determines the online graphics display.  If MFTERM is not set, and DISPLAY is set, the Metafont window support for X is used. (DISPLAY must be set to a valid X server specification, as usual.) If neither MFTERM nor DISPLAY is set, TERM is used to guess the window support to use.

Font Utilities

A number of utility programs are available. The following is a partial list of available utilities and their purpose. Consult your local Metafont guru for details.


Takes a gf file and produces a more tightly packed pk font file.


Produces proof sheets for fonts.


Displays the contents of a gf file in mnemonics and/or images.


Mnemonically displays the contents of a pk file.


Formats a source file as shown in Computer Modern Typefaces.



Encoded text of Metafont's messages.


Predigested Metafont base files.


The standard base.


The file of mode_defs for your site's various printers


This manual page is not meant to be exhaustive.  The complete documentation for this version of Metafont can be found in the info manual Web2C: A TeX implementation.


On January 4, 1986 the “final” bug in Metafont was discovered and removed.  If an error still lurks in the code, Donald E. Knuth promises to pay a finder's fee which doubles every year to the first person who finds it.  Happy hunting.

Suggested Reading

Donald E. Knuth, The Metafontbook (Volume C of Computers and Typesetting), Addison-Wesley, 1986, ISBN 0-201-13445-4.
Donald E. Knuth, Metafont: The Program (Volume D of Computers and Typesetting), Addison-Wesley, 1986, ISBN 0-201-13438-1.
Donald E. Knuth, Computer Modern Typefaces (Volume E of Computers and Typesetting), Addison-Wesley, 1986, ISBN 0-201-13446-2.
TUGboat (the journal of the T E X Users Group).


Warning: “Type design can be hazardous to your other interests. Once you get hooked, you will develop intense feelings about letterforms; the medium will intrude on the messages that you read. And you will perpetually be thinking of improvements to the fonts that you see everywhere, especially those of your own design.”

See Also

gftopk(1), gftodvi(1), gftype(1), mft(1), mpost(1), pltotf(1), tftopl(1).


Metafont was designed by Donald E. Knuth, who implemented it using his WEB system for Pascal programs.  It was originally ported to Unix by Paul Richards at the University of Illinois at Urbana-Champaign.  This page was mostly written by Pierre MacKay.

Referenced By

aleph(1), dvips(1), dvisvgm(1), etex(1), gftodvi(1), gftopk(1), gftype(1), hitex(1), mft(1), mftrace(1), mktextfm(1), mpost(1), pdfjadetex(1), pdftex(1), tex(1), texconfig(1).

The man pages inimf(1) and mf-nowin(1) are aliases of mf(1).

6 August 2019 Web2C 2023