任务是使用INET域编写一个程序，所以我做到了。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"，则服务器将向客户端发送在服务器的主办
该程序在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);
}
但是如何获得C中任何命令的正常运行时间呢？
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 = %ldn", connected.uptime);
bytes_recieved = recv(connected,recv_data,1024,0);
recv_data[bytes_recieved] = ' ';
}
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] = ' ';
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;
}
修改：
/* 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] = ' ';
if (strcmp(recv_data , "u") == 0 || strcmp(recv_data , "U") == 0)
{
if (sysinfo(&info) == 0) {
snprintf(send_data, sizeof send_data, "Uptime: %ld secondsn", info.uptime);
} else {
snprintf(send_data, sizeof send_data, "Error getting uptime: %sn", strerror(errno));
}
send(connected, send_data,strlen(send_data), 0);
}
}
close(sock);
return 0;
}
}
您不应该执行uptime命令，而是从代码中调用API来获取uptime，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 secondsn", info.uptime);
} else {
snprintf(send_data, sizeof send_data, "Error getting uptime: %sn", strerror(errno));
}
send(sock, send_data, strlen(send_data), 0);