Most command line programs accept parameters like
--help (originally from Unix) or
/? (originally from Windows) that list their common options.
pdftex, which is
latex these days) is not an exception and recognizes
--help. The same applies to other TeX engines like
On Unix, you can also type
man pdftex etc. to read these programs' manual pages. MikTeX has them online; and TeX Live has the man pages in PDF format on your computer.
Modern TeX distributions (e.g. MiKTeX and TeX Live) have a
texdoc command line tool. You can use
to get the document of
pdflatex. Similarly, you can use
texdoc --help or even
texdoc texdoc to get help of the