README

           minishell: Re-implementation of a UNIX Shell

minishell is a re-implementation of Bash-like UNIX shell. The purpose
of this project is to learn about system calls for creating, managing,
and coordinating processes. Features of minishell includes: parsing of
command lines, execution of foreground commands, conditional comamnds,
I/O redirections, pipes, and command interruption through signals.

minishell command line has the following BNF grammer:

<commandline> ::= <list>
        |  <list> ";"
        |  <list> "&"

<list> ::= <andor>
        |  <list> ";" <andor>
        |  <list> "&" <andor>

<andor> ::= <pipeline>
        |  <andor> "&&" <pipeline>
        |  <andor> "||" <pipeline>

<pipeline> ::=  <command>
        |  <pipeline> "|" <command>

<command>  ::=  <word>
        |  <redirection_list>
        |  <command> <word>
        |  <command> <redirection_list>

<redirection_list> ::= <io_redirection>
        |  <redirection_list> <io_redirection>

<io_redirection> ::= <redirection_op> <filename>

<redirection_op> ::= "<" | ">" | ">>"

BUILTINS

The following builtin commands are implemented: echo, cd, pwd, export,
unset, env, exit.