File: grep.info,  Node: Command-line Options,  Next: Environment Variables,  Up: Invoking

2.1 Command-line Options
========================

‘grep’ comes with a rich set of options: some from POSIX and some being
GNU extensions.  Long option names are always a GNU extension, even for
options that are from POSIX specifications.  Options that are specified
by POSIX, under their short names, are explicitly marked as such to
facilitate POSIX-portable programming.  A few option names are provided
for compatibility with older or more exotic implementations.

* Menu:

* Generic Program Information::
* Matching Control::
* General Output Control::
* Output Line Prefix Control::
* Context Line Control::
* File and Directory Selection::
* Other Options::

   Several additional options control which variant of the ‘grep’
matching engine is used.  *Note grep Programs::.