The input file specification indicates the file to be formatted; TeX uses `.tex' as a default file extension. If you omit the input file entirely, TeX accepts input from the terminal. You specify command options by supplying a string as a parameter to the command. eg.
latex "\scrollmode\input foo.tex"
...will process `foo.tex' without pausing after every error.
Output files are always created in the current directory. When you fail
to specify an input file name, TeX bases the output names on the file
specification associated with the logical name TEX_OUTPUT, typically
texput.log.