完成基本shall功能的小程序

文件:	myshell.c.tar.gz
大小:	1KB
下载:	下载

本程序完成基本shall功能，如ls,cd等功能。

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <sys/types.h>


#define DIRBUF_SIZE 1024

char * readConsel(void)        //从终端得到一行命令，并返回地址

{
    char *ptr = NULL;
    int ret;
    size_t n;

    ret = getline(&ptr, &n, stdin);    /*若ptr=NULL,getline函数malloc出一段动态内存，故使用完后要free掉，同时ptr,n的值都会被更新*/
    if (ret == -1)
    {
        ptr = NULL;
    }
    
    return ptr;

}

int caculateCmdNum(char *buf)        //返回字符串数量

{
    int i = 0, cnt = 0;

    while (1)
    {
        if (buf[i] == 0)
            break;
        if (buf[i] == ' ')
        {
            i++;    
            continue;
        }
        else
        {
            if ((i != 0) && (buf[i-1] == ' '))
                cnt += 1;
            else if (i == 0)
                cnt += 1;
        }

        i++;
    }
    return cnt;
}

int ifChdir(char **argv)    /*判断是否是cd,若是执行cd操作*/
{
    if (strcmp(argv[0], "cd") == 0) {
        chdir(argv[1]);
        return 1;
    }    
        

    else
        return 0;
}

void parseCommand(char *buf)
{
    int ret, cnt, i = 0;
    char *ptr = buf;
    char *retptr = NULL;
    char *delimit = " ";

    cnt = caculateCmdNum(buf);
    if (cnt == 0)
        return;
    
    char *argv[cnt+1];


    while (1) {
        retptr = strtok(ptr, delimit);
        if (retptr)
            argv[i++] = retptr;
        else
            break;
        ptr = NULL;
    }
    argv[cnt] = NULL;
    if (ifChdir(argv))
        return;

    pid_t pid = fork();
    if (pid == -1)
    {
        perror("fork");
        exit(-1);
    }
    if (pid == 0)
        ret = execvp(argv[0], argv);

    wait(NULL);
}

void showmyshall(void)
{
    char buf[DIRBUF_SIZE];
    if(getcwd(buf,DIRBUF_SIZE)==NULL)
    {
        perror("getcwd");
        exit(-1);
    }
    printf("myshall:~%s$ ",buf);
    fflush(stdout);
}

int main(void)
{
    char *buf = NULL;

    while (1) {
        showmyshall();
        buf = readConsel();
        if (buf) {    
            buf[strlen(buf)-1] = '\0';
            parseCommand(buf);
            free(buf);
        }
    }

}

运行结果：

zx@zhangxu:~/ad_programming/proc/homework$ ./test
myshall:~/home/zx/ad_programming/proc/homework$ ls
dup2.c    myshell.c test tmp
myshall:~/home/zx/ad_programming/proc/homework$ vi tmp
myshall:~/home/zx/ad_programming/proc/homework$ cd ..
myshall:~/home/zx/ad_programming/proc$ cd homework
myshall:~/home/zx/ad_programming/proc/homework$ ^C
zx@zhangxu:~/ad_programming/proc/homework$