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 TeX, 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
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 TeX, 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.
\&\h'|\n(40u'\s-2MAGSTEP\s0\h'|\n(41u'118 dpi\h'|\n(42u'240 dpi\h'|\n(43u'300 dpi \&\h'|\n(40u'mag=magstep(0)\h'|\n(41u'118\h'|\n(42u'240\h'|\n(43u'300 \&\h'|\n(40u'mag=magstep(0.5)\h'|\n(41u'129\h'|\n(42u'263\h'|\n(43u'329 \&\h'|\n(40u'mag=magstep(1)\h'|\n(41u'142\h'|\n(42u'288\h'|\n(43u'360 \&\h'|\n(40u'mag=magstep(2)\h'|\n(41u'170\h'|\n(42u'346\h'|\n(43u'432 \&\h'|\n(40u'mag=magstep(3)\h'|\n(41u'204\h'|\n(42u'415\h'|\n(43u'518 \&\h'|\n(40u'mag=magstep(4)\h'|\n(41u'245\h'|\n(42u'498\h'|\n(43u'622 \&\h'|\n(40u'mag=magstep(5)\h'|\n(41u'294\h'|\n(42u'597\h'|\n(43u'746