实验代码

#include <stdio.h>
#include <string.h>
void exec(char cmd[])
{
    int f = 0, i, l;
    l = strlen(cmd);
    for (i = 0; i < l; i++)
    {
        if (cmd[i] == ‘|‘)
        {
            f = 1;
            break;
        }
    }
    if (!f)
    {
        system(cmd);
    }
    else
    {
        FILE *fr, *fw;
        char commands[2][256];
        char result[256];
        cmd[l] = ‘|‘;
        int k, n;
        k = 0;
        n = 0;
        for (i = 0; i <= l; i++)
        {
            if (cmd[i] != ‘|‘)
            {
                commands[n][k] = cmd[i];
                k++;
            }
            else
            {
                commands[n][k] = ‘\0‘;
                k = 0;
                n++;
            }
        }
        fr = popen(commands[0], "r");
        fw = popen(commands[1], "w");
        fread(result, 256 * sizeof(char), 1, fr);
        fwrite(result, sizeof(char), strlen(result), fw);
        pclose(fr);
        pclose(fw);
    }
}

int main()
{
    char cmd[256], c;
    int i;
    while (1)
    {
        printf("OSLab2 -> ");
        i = 0;
        while ((c = getchar()) != ‘\n‘)
        {
            if (c != ‘;‘)
            {
                cmd[i] = c;
                i++;
            }
            else
            {
                cmd[i] = ‘\0‘;
                exec(cmd);
                i = 0;
            }
        }
        cmd[i] = ‘\0‘;
        if (strcmp(cmd, "exit"))
        {
            exec(cmd);
        }
        else
        {
            break;
        }
    }
    return 0;
}