The command-line syntax is
{ftangle | fweave} [-option...] webfile[.web] [changefile[.ch]]
A file name is anything that doesn’t begin with a ‘-’, except that a lone hyphen stands for the special file name stdin, which means ‘read from the standard input.’ (This should not be used except for very special effects.)
Command-line options begin with a ‘-’. File names and options can be intermixed, or the options may appear after the file names. The first file name encountered is the web source file; the second, if it exists, is the change file (see Change files). [When no change file is specified, FWEB attempts to read from the null file (/dev/null on UNIX systems). This name should be specified when FWEB is installed (see Customization), or can be set in the style file fweb.sty. See null_file.]
The web file is shown as required since one is normally processing a source. However, some of the information options (see Info options) will work without specifying any file name. For example, one can obtain a list of all of the style-file parameters and their default values by saying ‘ftangle -Z’.