If you type the name of the program alone on the command line:
mfthen mf displays a `**' prompt, which `is 's way of asking you for an input file name'. (See The book, Chapter 5: `Running '.) Thus, to process a file named fred.mf, you may type:
fred
A backslash (`\') can also be typed here. This causes all subsequent commands at the prompt line to be interpreted as in a file. (Concerning the backslash, see The book, Chapter 20: `More About Macros', pages 179 and 180 in the 1986 edition.) Thus we can respond to the ** prompt with:
\ input fredor even:
\ ; input fred
The backslash is useful because certain commands are often executed before a file is input. In particular, quality printing (see subsection below) requires the command mode, and output magnification (subsection ) employs the mag command. For example:
\mode=localfont; mag=magstep(1); input fred
To read MS-DOS pathnames at the ** prompt, this satisfies :
\input \seldom\fred.mfas does:
d:\seldom\fred.mf