---
name: "freebsd-yacc"
section: "1"
platform: "linux"
package: "freebsd-buildutils"
version: "9.0-11"
release: "Debian 7 (Wheezy)"
platforms: ["linux"]
url: "https://new.carta.tech/freebsd-yacc"
---

# freebsd-yacc(1)

an LALR(1) parser generator

## NAME

**yacc** – an LALR(1) parser generator

## SYNOPSIS

**yacc** \[**-dlrtvy**\] \[**-b** *file\_prefix*\] \[**-o** *output\_filename*\] \[**-p** *symbol\_prefix*\] *filename*

## DESCRIPTION

The **yacc** utility reads the grammar specification in the file *filename* and generates an LR(1) parser for it. The parsers consist of a set of LALR(1) parsing tables and a driver routine written in the C programming language. The **yacc** utility normally writes the parse tables and the driver routine to the file *y.tab.c*.

The following options are available:

- **-b** *file\_prefix*

  Change the prefix prepended to the output file names to the string denoted by *file\_prefix*. The default prefix is the character *y*.

- **-d**

  Cause the header file *y.tab.h* to be written.

- **-l**

  If the **-l** option is not specified, **yacc** will insert #line directives in the generated code. The #line directives let the C compiler relate errors in the generated code to the user's original code. If the **-l** option is specified, **yacc** will not insert the #line directives. Any #line directives specified by the user will be retained.

- **-o** *output\_filename*

  Cause **yacc** to write the generated code to *output\_filename* instead of the default file, *y.tab.c*.

- **-p** *symbol\_prefix*

  Change the prefix prepended to yacc-generated symbols to the string denoted by *symbol\_prefix*. The default prefix is the string *yy*.

- **-r**

  Cause **yacc** to produce separate files for code and tables. The code file is named *y.code.c*, and the tables file is named *y.tab.c*.

- **-t**

  Change the preprocessor directives generated by **yacc** so that debugging statements will be incorporated in the compiled code.

- **-v**

  Cause a human-readable description of the generated parser to be written to the file *y.output*.

- **-y**

  NOOP for bison compatibility. **yacc** is already designed to be POSIX yacc compatible.

## ENVIRONMENT

- TMPDIR

  Name of directory where temporary files are to be created.

## TABLES

The names of the tables generated by this version of **yacc** are *yylhs*, *yylen*, *yydefred*, *yydgoto*, *yysindex*, *yyrindex*, *yygindex*, *yytable*, and *yycheck*. Two additional tables, *yyname* and *yyrule*, are created if YYDEBUG is defined and non-zero.

## FILES

- *y.code.c*

  - *y.tab.c*

  - *y.tab.h*

  - *y.output*

  - */tmp/yacc.aXXXXXXXXXX*

  - */tmp/yacc.tXXXXXXXXXX*

  - */tmp/yacc.uXXXXXXXXXX*

  ## DIAGNOSTICS

If there are rules that are never reduced, the number of such rules is reported on standard error. If there are any LALR(1) conflicts, the number of conflicts is reported on standard error.

## SEE ALSO

[yyfix(1)](/yyfix/1.md)

## STANDARDS

The **yacc** utility conforms to IEEE Std 1003.2 (“POSIX.2”).

## HISTORY

A **yacc** command appeared in PWB UNIX.