Untitled

     1. COMMAND_LINE -> COMPLETE_COMMAND PIPED_CMD
     2. PIPED_CMD -> PIPE COMPLETE_COMMAND PIPED_CMD
     3.            | ε
     4. COMPLETE_COMMAND -> CMD_PREFIX CMD CMD_SUFFIX
     5. CMD_PREFIX -> REDIRECTION CMD_PREFIX
     6.             | ε
     7. CMD_SUFFIX -> REDIRECTION CMD_SUFFIX
     8.             | CMD_ARG
     9.             | ε
    10. REDIRECTION -> REDIRECTION_OP WORD
    11. CMD -> WORD
    12. CMD_ARG -> WORD CMD_ARG
    13.          | SINGLE_QUOTE WORD DOUBLE_QUOTE CMD_ARG
    14.          | DOUBLE_QUOTE WORD DOUBLE_QUOTE CMD_ARG
    15.          | ε
    16. REDIRECTION_OP -> HERE_DOC
    17.                 | APPEND
    18.                 | INFILE
    19.                 | OUTFILE