9.5.5 input option

This is the "input file to search for defs" option.

This option has some usage constraints. It:

• is required to appear on the command line.
• may appear an unlimited number of times.

All files that are to be searched for definitions must be named on the command line or read from stdin. If there is only one input option and it is the string, "-", then the input file list is read from stdin. If a command line argument is not an option name and does not contain an assignment operator (=), then it defaults to being an input file name. At least one input file must be specified.