term% ls -F
term% pwd
term% cat index.txt
YACC(1)                     General Commands Manual                    YACC(1)

       yacc - yet another compiler-compiler

       yacc [ -vd ] grammar

       Yacc  converts a context-free grammar into a set of tables for a simple
       automaton which executes an LR(1) parsing algorithm.  The  grammar  may
       be ambiguous; specified precedence rules are used to break ambiguities.

       The output file,, must be compiled by the C compiler to produce
       a program yyparse.  This program must be loaded with the  lexical  ana‐
       lyzer  program,  yylex,  as well as main and yyerror, an error handling
       routine.  These routines must be supplied by the user; Lex(1) is useful
       for creating lexical analyzers usable by yacc.

       If  the -v flag is given, the file y.output is prepared, which contains
       a description of the parsing tables and a report on conflicts generated
       by ambiguities in the grammar.

       If  the  -d flag is used, the file is generated with the define
       statements that associate the  yacc-assigned  `token  codes'  with  the
       user-declared  `token  names'.   This  allows  source  files other than to access the token codes.

       y.output             defines for token names
       yacc.tmp, yacc.acts temporary files
       /usr/lib/yaccpar    parser prototype for C programs
       /lib/liby.a         library with default `main' and `yyerror'

       LR Parsing by A. V. Aho and S. C.  Johnson,  Computing  Surveys,  June,
       YACC - Yet Another Compiler Compiler by S. C. Johnson.

       The  number  of reduce-reduce and shift-reduce conflicts is reported on
       the standard output; a more detailed report is found  in  the  y.output
       file.   Similarly,  if some rules are not reachable from the start sym‐
       bol, this is also reported.

       Because file names are fixed, at most one yacc process can be active in
       a given directory at a time.