grammar

/*----------------------------------*/
/*              TOKENS              */
/*----------------------------------*/

%token    WORD
%token    ASSIGNMENT_WORD
%token    IO_NUMBER

%token    SEMICOLON    BG
/*        ';'          '&'                                        */
%token    AND_IF    OR_IF
/*        '&&'      '||'                                          */
%token    PIPE
/*        '|'                                                     */
%token    SLESS    SGREAT    DLESS    DGREAT    LESSAND    GREATAND
/*        '<'      '>'       '<<'     '>>'      '<&'       '>&'   */


/*----------------------------------*/
/*              GRAMMAR             */
/*----------------------------------*/

%start      complete_command
%%
complete_command    ::=    list

list                ::=    and_or [separator_op and_or]* separator_op?

and_or              ::=    pipe_sequence [[AND_IF | OR_IF] pipe_sequence]*

pipe_sequence       ::=    command [PIPE command]*

command             ::=    [cmd_prefix [cmd_word [cmd_suffix]?]?] | [cmd_word cmd_suffix?]
       
cmd_prefix          ::=    [io_redirect | ASSIGNMENT_WORD]*

io_redirect         ::=    IO_NUMBER? [io_file | io_here]

io_file             ::=    [SLESS | SGREAT | LESSAND | GREATAND | DGREAT] filename

filename            ::=    WORD

io_here             ::=    DLESS here_end

here_end            ::=    WORD

cmd_word            ::=    WORD

cmd_suffix          ::=    [io_redirect | WORD]*

separator_op        ::=    BG | SEMICOLON