9. Invoking Bison

The usual way to invoke Bison is as follows:

bison infile

Here infile is the grammar file name, which usually ends in `.y'. The parser file's name is made by replacing the `.y' with `.tab.c'. Thus, the `bison foo.y' filename yields `foo.tab.c', and the `bison hack/foo.y' filename yields `hack/foo.tab.c'. It's is also possible, in case you are writting C++ code instead of C in your grammar file, to name it `foo.ypp' or `foo.y++'. Then, the output files will take an extention like the given one as input (repectively `foo.tab.cpp' and `foo.tab.c++'). This feature takes effect with all options that manipulate filenames like `-o' or `-d'.

For example :

bison -d infile.yxx

will produce `infile.tab.cxx' and `infile.tab.hxx'. and

bison -d infile.y -o output.c++

will produce `output.c++' and `outfile.h++'.

9.1 Bison Options		All the options described in detail, in alphabetical order by short options.
9.2 Environment Variables		Variables which affect Bison execution.
9.3 Option Cross Key		Alphabetical list of long options.
9.4 Invoking Bison under VMS		Bison command syntax on VMS.

9.1 Bison Options

Bison supports both traditional single-letter options and mnemonic long option names. Long option names are indicated with `--' instead of `-'. Abbreviations for option names are allowed as long as they are unique. When a long option takes an argument, like `--file-prefix', connect the option name and the argument with `='.

Here is a list of options that can be used with Bison, alphabetized by short option. It is followed by a cross key alphabetized by long option.

Operations modes:

`-h'

`--help'

Print a summary of the command-line options to Bison and exit.

`-V'

`--version'

Print the version number of Bison and exit.

`-y'

`--yacc'

`--fixed-output-files'

Equivalent to `-o y.tab.c'; the parser output file is called `y.tab.c', and the other outputs are called `y.output' and `y.tab.h'. The purpose of this option is to imitate Yacc's output file name conventions. Thus, the following shell script can substitute for Yacc:

bison -y $*

Tuning the parser:

`-S file'

`--skeleton=file'

Specify the skeleton to use. You probably don't need this option unless you are developing Bison.

`-t'

`--debug'

Output a definition of the macro YYDEBUG into the parser file, so that the debugging facilities are compiled. See section Debugging Your Parser.

`--locations'

Pretend that %locactions was specified. See section 3.7.8 Bison Declaration Summary.

`-p prefix'

`--name-prefix=prefix'

Rename the external symbols used in the parser so that they start with prefix instead of `yy'. The precise list of symbols renamed is yyparse, yylex, yyerror, yynerrs, yylval, yychar and yydebug.

For example, if you use `-p c', the names become cparse, clex, and so on.

See section Multiple Parsers in the Same Program.

`-l'

`--no-lines'

Don't put any #line preprocessor commands in the parser file. Ordinarily Bison puts them in the parser file so that the C compiler and debuggers will associate errors with your source file, the grammar file. This option causes them to associate errors with the parser file, treating it as an independent source file in its own right.

`-n'

`--no-parser'

Pretend that %no_parser was specified. See section 3.7.8 Bison Declaration Summary.

`-k'

`--token-table'

Pretend that %token_table was specified. See section 3.7.8 Bison Declaration Summary.

Adjust the output:

`-d'

Pretend that %verbose was specified, i.e., write an extra output file containing macro definitions for the token type names defined in the grammar and the semantic value type YYSTYPE, as well as a few extern variable declarations. See section 3.7.8 Bison Declaration Summary.

`--defines=defines-file'

The behaviour of --defines is the same than `-d'. The only difference is that it has an optionnal argument which is the name of the output filename.

`-b file-prefix'

`--file-prefix=prefix'

Specify a prefix to use for all Bison output file names. The names are chosen as if the input file were named `prefix.c'.

`-v'

`--verbose'

Pretend that %verbose was specified, i.e, write an extra output file containing verbose descriptions of the grammar and parser. See section 3.7.8 Bison Declaration Summary, for more.

`-o outfile'

`--output-file=outfile'

Specify the name outfile for the parser file.

The other output files' names are constructed from outfile as described under the `-v' and `-d' options.

`-g'

Output a VCG definition of the LALR(1) grammar automaton computed by Bison. If the grammar file is `foo.y', the VCG output file will be `foo.vcg'.

`--graph=graph-file'

The behaviour of --graph is the same than `-g'. The only difference is that it has an optionnal argument which is the name of the output graph filename.

9.2 Environment Variables

Here is a list of environment variables which affect the way Bison runs.

`BISON_SIMPLE'

`BISON_HAIRY'

Much of the parser generated by Bison is copied verbatim from a file called `bison.simple'. If Bison cannot find that file, or if you would like to direct Bison to use a different copy, setting the environment variable BISON_SIMPLE to the path of the file will cause Bison to use that copy instead.

When the `%semantic_parser' declaration is used, Bison copies from a file called `bison.hairy' instead. The location of this file can also be specified or overridden in a similar fashion, with the BISON_HAIRY environment variable.

9.3 Option Cross Key

Here is a list of options, alphabetized by long option, to help you find the corresponding short option.

--debug -t --defines=defines-file -d --file-prefix=prefix -b file-prefix --fixed-output-files --yacc -y --graph=graph-file -d --help -h --name-prefix=prefix -p name-prefix --no-lines -l --no-parser -n --output-file=outfile -o outfile --token-table -k --verbose -v --version -V

9.4 Invoking Bison under VMS

The command line syntax for Bison on VMS is a variant of the usual Bison command syntax--adapted to fit VMS conventions.

To find the VMS equivalent for any Bison option, start with the long option, and substitute a `/' for the leading `--', and substitute a `_' for each `-' in the name of the long option. For example, the following invocation under VMS:

bison /debug/name_prefix=bar foo.y

is equivalent to the following command under POSIX.

bison --debug --name-prefix=bar foo.y

The VMS file system does not permit filenames such as `foo.tab.c'. In the above example, the output file would instead be named `foo_tab.c'.