编程实现linux下的shell

/*************************************************************************

    > File Name: Kris_shell.c

    > Author: KrisChou

    > Mail:[email protected] 

    > Created Time: Thu 21 Aug 2014 04:31:55 PM CST

 ************************************************************************/



#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <unistd.h>

#include <sys/wait.h>



#define PROMPT ">>" 

#define ARG_CNT 32



void command_to_arglist(char** arglist,char *cmd_line);

int main(int argc, char *argv[])

{

    char cmd_line[1024];

    char *arglist[ARG_CNT];

    while(memset(cmd_line,0,1024), printf("%s",PROMPT), fgets(cmd_line,1024,stdin))

    {

        if(cmd_line[0] != '\n')

        {

            cmd_line[strlen(cmd_line) - 1] = '\0'; //将读进来的换行符变成'\0'

            command_to_arglist(arglist,cmd_line);

            if(fork() > 0)

            {

                wait(NULL);

            }else

            {

                execvp(arglist[0],arglist);

                exit(0);

            }

        }

    }

    return 0;

}



static int my_isspace(char c)

{

    if(c == ' '|| c == '\n' || c == '\t' || c =='\v')

        return 1;

    else

        return 0;

}

static void command_to_arglist(char** arglist,char *cmd_line)

{

    int cnt = 0;

    int bg,end;

    bg = 0;

    while(cmd_line[bg] != '\0')

    {

        while(my_isspace(cmd_line[bg]))

        {

            bg++;

        }

        if(cmd_line[bg] == '\0')

        {

            break;

        }

        end = bg;

        while(cmd_line[end] != '\0' && !my_isspace(cmd_line[end]))

        {

            end++;

        }

        arglist[cnt] = (char*)calloc(1, (end-bg+1));

        strncpy(arglist[cnt],cmd_line+bg,(end-bg));

        cnt++;

        bg = end;

    }

    arglist[cnt] = NULL;

    

}