Question

任务是使用INET域编写程序，所以我做了。但有一件小事要做，我不知道如何表演。输入行的第一个非空白字符是'u'，服务器将向客户端发送在服务器上执行的'uptime'命令的输出主办。

程序在Linux（Ubuntu）下运行。

可能是这样的：

    if (strcmp(send_data , "u") == 0 || strcmp(send_data , "U") == 0)
    {
        send(sock, uptimevar, strlen(uptimevar), 0);               
    }

但是如何在C中获得任何命令的正常运行时间？

服务器代码：

/* tcpserver.c */

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/sysinfo.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>

int main()
{
int sock, connected, bytes_recieved , true = 1;  
char send_data [1024] , recv_data[1024];       

struct sockaddr_in server_addr,client_addr/*, sysinfo*/;    
int sin_size;

if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
    perror("Socket");
    exit(1);
}

if (setsockopt(sock,SOL_SOCKET,SO_REUSEADDR,&true,sizeof(int)) == -1) {
    perror("Setsockopt");
    exit(1);
}

server_addr.sin_family = AF_INET;         
server_addr.sin_port = htons(1237);     
server_addr.sin_addr.s_addr = INADDR_ANY; 
bzero(&(server_addr.sin_zero),8); 

if (bind(sock, (struct sockaddr *)&server_addr, sizeof(struct sockaddr))
                                                               == -1) {
    perror("Unable to bind");
    exit(1);
}

if (listen(sock, 5) == -1) {
    perror("Listen");
    exit(1);
}

printf ("\nTCPServer Waiting for client on port 5000");
    fflush(stdout);
while(1)
{  

    sin_size = sizeof(struct sockaddr_in);

    connected = accept(sock, (struct sockaddr *)&client_addr,&sin_size);

    printf("\n I got a connection from (%s , %d)",
           inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port));

    while (1)
    {
        printf("\n SEND (q or Q to quit) : ");
        fgets(send_data, sizeof(send_data), stdin);

        if (strcmp(send_data , "q") == 0 || strcmp(send_data , "Q") == 0)
        {
          send(connected, send_data,strlen(send_data), 0); 
          close(connected);
          break;
        }

        else 
        {
            send(connected, send_data,strlen(send_data), 0);  
            //printf("Uptime = %ld\n", connected.uptime);

            bytes_recieved = recv(connected,recv_data,1024,0);

            recv_data[bytes_recieved] = '\0';
        }
        if (strcmp(recv_data , "q") == 0 || strcmp(recv_data , "Q") == 0)
        {
          close(connected);
          break;
        }

        else {
            printf("\n RECIEVED DATA = %s " , recv_data);
            fflush(stdout);   
        }
    }
}       
close(sock);
return 0;
}

客户代码：

/* tcpclient.c */

#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>


int main()
{

int sock, bytes_recieved;  
char send_data[1024],recv_data[1024];
struct hostent *host;
struct sockaddr_in server_addr;  

host = gethostbyname("127.0.0.1");

if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
    perror("Socket");
    exit(1);
}

server_addr.sin_family = AF_INET;     
server_addr.sin_port = htons(1237);   
server_addr.sin_addr = *((struct in_addr *)host->h_addr);
bzero(&(server_addr.sin_zero),8); 

if (connect(sock, (struct sockaddr *)&server_addr,
            sizeof(struct sockaddr)) == -1) 
{
    perror("Connect");
    exit(1);
}

while(1)
{
    bytes_recieved=recv(sock,recv_data,1024,0);
    recv_data[bytes_recieved] = '\0';

    if (strcmp(recv_data , "q") == 0 || strcmp(recv_data , "Q") == 0)
    {
        close(sock);
        break;
    }

    else 
    {
        printf("\nRecieved data = %s " , recv_data);
        printf("\nSEND (q or Q to quit) : ");
        fgets(send_data, sizeof(send_data), stdin);
    } 
    if (strcmp(send_data , "q") == 0 || strcmp(send_data , "Q") == 0)
    {
        send(sock, send_data, strlen(send_data), 0);   
        close(sock);            
        break;
    }
    else
    {
        send(sock,send_data, strlen(send_data), 0);           
    }
}   
return 0;
}

修饰：

/* tcpserver.c */

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/sysinfo.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>

int main()
{
int sock, connected, bytes_recieved , true = 1;  
char send_data [1024] , recv_data[1024];       
struct sockaddr_in server_addr,client_addr/*, sysinfo*/; 
struct sysinfo info;   
int sin_size;

if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
    perror("Socket");
    exit(1);
}

if (setsockopt(sock,SOL_SOCKET,SO_REUSEADDR,&true,sizeof(int)) == -1) {
    perror("Setsockopt");
    exit(1);
}

server_addr.sin_family = AF_INET;         
server_addr.sin_port = htons(1237);     
server_addr.sin_addr.s_addr = INADDR_ANY; 
bzero(&(server_addr.sin_zero),8); 

if (bind(sock, (struct sockaddr *)&server_addr, sizeof(struct sockaddr))
                                                               == -1) {
    perror("Unable to bind");
    exit(1);
}

if (listen(sock, 5) == -1) {
    perror("Listen");
    exit(1);
}

printf ("\nTCPServer Waiting for client on port 1237");
    fflush(stdout);
while(1)
{  

    sin_size = sizeof(struct sockaddr_in);

    connected = accept(sock, (struct sockaddr *)&client_addr,&sin_size);

    //sysinfo(&connected);
    printf("\n I got a connection from (%s , %d)",
           inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port));
    send(connected, "Hello this is a simple server", 100, 1);

    while (1)
    {
        printf("\n SEND (q or Q to quit) : ");
        fgets(send_data, sizeof(send_data), stdin);

        bytes_recieved = recv(connected,recv_data,1024,0);
        recv_data[bytes_recieved] = '\0';

        if (strcmp(recv_data , "u") == 0 || strcmp(recv_data , "U") == 0)
            {
            if (sysinfo(&info) == 0) {
               snprintf(send_data, sizeof send_data, "Uptime: %ld seconds\n", info.uptime);
            } else {
               snprintf(send_data, sizeof send_data, "Error getting uptime: %s\n", strerror(errno));
            }
            send(connected, send_data,strlen(send_data), 0);  
        }

    }       
    close(sock);
    return 0;
}
}

Answer 1

你不应该执行uptime命令，而是从代码中调用API来获得正常运行时间，在linux上这是通过sysinfo（）函数完成的。

#include <sys/sysinfo.h>
...

struct sysinfo info

if (sysinfo(&info) == 0) {
   snprintf(send_data, sizeof send_data, "Uptime: %ld seconds\n", info.uptime);
} else {
   snprintf(send_data, sizeof send_data, "Error getting uptime: %s\n", strerror(errno));
}

send(sock, send_data, strlen(send_data), 0);

如何在socket中获得命令的正常运行时间

1 个答案: