A simple simulation of shell in Linux for learning.

A blog (in Chinese) of introduction and how to build it :http://www.cnblogs.com/wuyuegb2312/p/3399566.html

usage:
============
type
　　make wshell
for wshell read input by fgets() or
　　make wshell_r
for wshell with readline lib.It need to install libreadline5-dev first.

Attention:

　　Because of the lack of support for regular expressions , file's names such as *.c are not support.

consist of:
============
-wshell.c
　　main program

-type_prompt.c
　　print out the prompt of wshell including path,hostname

-read_command.c
　　read command input, and analyse the command and parameter(s).

-builtin_command.c
　　support some built-in command,such as exit,quit,about, and cd.

-test.c
　　a test program, helloworld, which can be executed in wshell.

-parsing.c
　　analyses user's input line and tell them to wshell.

update log:
============

2014

5.14

    -Bug fix:

        In readline mode, the spaces alloced by readline() was freed only once.Now they are all freed in the end of read_command().

        As noted by xingfe123

 

4.14

    -Bug fix:

        Add handler of SIGCHLD. Earlier wshell would ignore the zombie process in background.

        The handler only process the background process whose pid are saved in a array.

     -Adjust some indents, although they are not errors.

 

2013

12.8

    -Bug fix:

        Output redirect function was not completed. '>' still is for make new file,but '>>' append to any file now.

 

11.3
    -Implemented a simple parsing function parse() to analyses the user input.
    -Support I/O redirect, background running, and pipe.
    -Bug fix:
        Typing ctrl+d will normal exit wshell. before, segment fault when using readline lib.

        Lack of free() somewhere, which may lead to memory leak.

 

11.1
    -Implemented some builtin command,such as exit/quit, about, and, cd.
    -Bug fix:
        Never free the memory of command and parameters before, which may cause memory leak.
        To solve it, read_command() has been rewrited, and is more like the one in Linux.
    -Rewrite read_command():
        There is no need to malloc for command and parameters any more.
        All these just are pointers now.
    -Supply two versions:
        Using readline lib and not.the former need installing readline lib.
        Type "make wshell_r" to make the former,and "make wshell" for another.

10.31
    -Use execvp() instead of execve() to handle with commands like ls.
    -Detect whether the shell is executed as root by geteuid()
    -Bug fix:
        execv()'s arg[0] usually is the name of command without path.
        earlier version is not correct.
    -Plan to do:
        a built-in cd command.

10.16
    -A shell with basic function: get input and execute the test program(hello world).