These are the options accepted by etags.  You may use unambiguous
abbreviations for the long option names.  A - as file name means read
names from stdin.  Absolute names are stored in the output file as they
are.  Relative ones are stored relative to the output file's directory.

-a, --append
        Append tag entries to existing tags file.
-C, --c++
        Treat files whose name suffix defaults to C language as C++ files.
-D, --no-defines
        Don't create tag entries for constant C #defines.  This makes
	the tags file smaller.
-i FILE, --include=FILE
        Include a note in tag file indicating that, when searching for
        a tag, one should also consult the tags file FILE after
        checking the current file.
-l LANG, --language=LANG
        Force the following files to be considered as written in the
	named language up to the next --language=LANG option.
-r /REGEXP/, --regex=/REGEXP/
        Make a tag for each line matching pattern REGEXP in the
 	following files.  REGEXP is anchored (as if preceded by ^).
	The form /REGEXP/NAME/ creates a named tag.  For example Tcl
	named tags can be created with:
	--regex=/proc[ \t]+\([^ \t]+\)/\1/.
-R, --no-regex
        Don't create tags from regexps for the following files.
-o FILE, --output=FILE
        Write the tags to FILE.
-I, --ignore-indentation
        Don't rely on indentation quite as much as normal.  Currently,
        this means not to assume that a closing brace in the first
        column is the final brace of a function or structure
        definition in C and C++.
-V, --version
        Print the version of the program.
-h, --help
        Print this help message.

These are the currently supported languages, along with the
default file name suffixes:
	asm	 .a .asm .def .inc .ins .s .sa .src
	c	 .c .h
	c++	 .C .H .c++ .cc .cpp .cxx .h++ .hh .hpp .hxx .M
	c*	 .cs .hs
	erlang	 .erl .hrl
	fortran	 .F .f .f90 .for
	lisp	 .cl .clisp .el .l .lisp .lsp .ml
	pascal	 .p .pas
	perl	 .pl .pm
	proc	 .pc .m .lm
	prolog	 .prolog
	scheme	 .SCM .SM .oak .sch .scheme .scm .sm .t
	tex	 .TeX .bib .clo .cls .ltx .sty .tex
	yacc	 .y .ym
	auto	
	none	
Where `auto' means use default language for files based on file
name suffix, and `none' means only do regexp processing on files.
If no language is specified and no matching suffix is found,
the first line of the file is read for a sharp-bang (#!) sequence
followed by the name of an interpreter.  If no such sequence is found,
Fortran is tried first; if no tags are found, C is tried next.
