/tmp/cc4QQlah.o：在函数‘main’中： web.c:(.text+0x255)：对‘peeror’未定义的引用

root@wangmiao:~/lesson# vim web.c
root@wangmiao:~/lesson# vim wrap.h
root@wangmiao:~/lesson# vim wrap.c

root@wangmiao:~/lesson# gcc web.c wrap.c -o web
web.c:9:20: fatal error: singnal.h: 没有那个文件或目录
 #include<singnal.h>
                    ^
compilation terminated.
wrap.c: In function ‘Accept’:
wrap.c:19:16: error: ‘ECONNABORTTED’ undeclared (first use in this function)
   if((errno == ECONNABORTTED)||(errno == EINTR))
                ^
wrap.c:19:16: note: each undeclared identifier is reported only once for each function it appears in
wrap.c: In function ‘Read’:
wrap.c:70:6: error: ‘error’ undeclared (first use in this function)
   if(error == EINTR)
      ^
wrap.c: In function ‘Write’:
wrap.c:87:6: error: ‘error’ undeclared (first use in this function)
   if(error == EINTR)
      ^
wrap.c: In function ‘my_read’:
wrap.c:176:3: error: ‘ptr’ undeclared (first use in this function)
  *ptr = *read_ptr++;
   ^
root@wangmiao:~/lesson# vim web.c
root@wangmiao:~/lesson# vim wrap.c
root@wangmiao:~/lesson# gcc web.c wrap.c -o web
In file included from web.c:11:0:
wrap.h:6:44: error: unknown type name ‘socklent_t’
 void Bind(int fd,const struct sockaddr *sa,socklent_t salen);
                                            ^
web.c: In function ‘http_send’:
web.c:34:2: warning: format ‘%S’ expects argument of type ‘wchar_t *’, but argument 3 has type ‘char *’ [-Wformat=]
  len = sprintf(HTTP_INFO,"%S%S",HTTP_HEADER,content);
  ^
web.c:34:2: warning: format ‘%S’ expects argument of type ‘wchar_t *’, but argument 4 has type ‘char *’ [-Wformat=]
web.c: In function ‘main’:
web.c:54:2: error: ‘listendfd’ undeclared (first use in this function)
  listendfd = Socket(AF_INET,SOCK_STREAM,0);
  ^
web.c:54:2: note: each undeclared identifier is reported only once for each function it appears in
web.c:55:25: error: ‘seraddr’ undeclared (first use in this function)
  bzero(&servaddr,sizeof(seraddr));
                         ^
web.c:61:22: error: ‘SOL_SOKET’ undeclared (first use in this function)
  setsockopt(listenfd,SOL_SOKET,SO_REUSEADDR,&opt,sizeof(opt));
                      ^
web.c:87:103: error: ‘cli_addr’ undeclared (first use in this function)
    printf("received from %s at PORT %d \n",inet_ntop(AF_INET,&cliaddr.sin_addr,str,sizeof(str)),ntohs(cli_addr.sin_port));
                                                                                                       ^
wrap.c: In function ‘Write’:
wrap.c:87:6: error: ‘error’ undeclared (first use in this function)
   if(error == EINTR)
      ^
wrap.c:87:6: note: each undeclared identifier is reported only once for each function it appears in
root@wangmiao:~/lesson# vim web.c
root@wangmiao:~/lesson# gcc web.c wrap.c -o -webone
In file included from web.c:11:0:
wrap.h:6:44: error: unknown type name ‘socklent_t’
 void Bind(int fd,const struct sockaddr *sa,socklent_t salen);
                                            ^
web.c: In function ‘http_send’:
web.c:34:2: warning: format ‘%S’ expects argument of type ‘wchar_t *’, but argument 3 has type ‘char *’ [-Wformat=]
  len = sprintf(HTTP_INFO,"%S%S",HTTP_HEADER,content);
  ^
web.c:34:2: warning: format ‘%S’ expects argument of type ‘wchar_t *’, but argument 4 has type ‘char *’ [-Wformat=]
web.c: In function ‘main’:
web.c:54:2: error: ‘listendfd’ undeclared (first use in this function)
  listendfd = Socket(AF_INET,SOCK_STREAM,0);
  ^
web.c:54:2: note: each undeclared identifier is reported only once for each function it appears in
web.c:55:25: error: ‘seraddr’ undeclared (first use in this function)
  bzero(&servaddr,sizeof(seraddr));
                         ^
web.c:61:22: error: ‘SOL_SOKET’ undeclared (first use in this function)
  setsockopt(listenfd,SOL_SOKET,SO_REUSEADDR,&opt,sizeof(opt));
                      ^
web.c:87:103: error: ‘cli_addr’ undeclared (first use in this function)
    printf("received from %s at PORT %d \n",inet_ntop(AF_INET,&cliaddr.sin_addr,str,sizeof(str)),ntohs(cli_addr.sin_port));
                                                                                                       ^
wrap.c: In function ‘Write’:
wrap.c:87:6: error: ‘error’ undeclared (first use in this function)
   if(error == EINTR)
      ^
wrap.c:87:6: note: each undeclared identifier is reported only once for each function it appears in
root@wangmiao:~/lesson# vim web.c
root@wangmiao:~/lesson# gcc web.c -o webtwo
In file included from web.c:11:0:
wrap.h:6:44: error: unknown type name ‘socklent_t’
 void Bind(int fd,const struct sockaddr *sa,socklent_t salen);
                                            ^
web.c: In function ‘http_send’:
web.c:34:2: warning: format ‘%S’ expects argument of type ‘wchar_t *’, but argument 3 has type ‘char *’ [-Wformat=]
  len = sprintf(HTTP_INFO,"%S%S",HTTP_HEADER,content);
  ^
web.c:34:2: warning: format ‘%S’ expects argument of type ‘wchar_t *’, but argument 4 has type ‘char *’ [-Wformat=]
web.c: In function ‘main’:
web.c:54:2: error: ‘listendfd’ undeclared (first use in this function)
  listendfd = Socket(AF_INET,SOCK_STREAM,0);
  ^
web.c:54:2: note: each undeclared identifier is reported only once for each function it appears in
web.c:55:25: error: ‘seraddr’ undeclared (first use in this function)
  bzero(&servaddr,sizeof(seraddr));
                         ^
web.c:61:22: error: ‘SOL_SOKET’ undeclared (first use in this function)
  setsockopt(listenfd,SOL_SOKET,SO_REUSEADDR,&opt,sizeof(opt));
                      ^
web.c:87:103: error: ‘cli_addr’ undeclared (first use in this function)
    printf("received from %s at PORT %d \n",inet_ntop(AF_INET,&cliaddr.sin_addr,str,sizeof(str)),ntohs(cli_addr.sin_port));
                                                                                                       ^
root@wangmiao:~/lesson# vim web.c
root@wangmiao:~/lesson# gcc web.c -o webtwo
In file included from web.c:11:0:
wrap.h:6:44: error: unknown type name ‘socklent_t’
 void Bind(int fd,const struct sockaddr *sa,socklent_t salen);
                                            ^
web.c: In function ‘main’:
web.c:54:2: error: ‘listendfd’ undeclared (first use in this function)
  listendfd = Socket(AF_INET,SOCK_STREAM,0);
  ^
web.c:54:2: note: each undeclared identifier is reported only once for each function it appears in
web.c:55:25: error: ‘seraddr’ undeclared (first use in this function)
  bzero(&servaddr,sizeof(seraddr));
                         ^
web.c:61:22: error: ‘SOL_SOKET’ undeclared (first use in this function)
  setsockopt(listenfd,SOL_SOKET,SO_REUSEADDR,&opt,sizeof(opt));
                      ^
web.c:87:103: error: ‘cli_addr’ undeclared (first use in this function)
    printf("received from %s at PORT %d \n",inet_ntop(AF_INET,&cliaddr.sin_addr,str,sizeof(str)),ntohs(cli_addr.sin_port));
                                                                                                       ^
root@wangmiao:~/lesson# vim web.c
root@wangmiao:~/lesson# gcc web.c -o webtwo
In file included from web.c:11:0:
wrap.h:6:44: error: unknown type name ‘socklent_t’
 void Bind(int fd,const struct sockaddr *sa,socklent_t salen);
                                            ^
root@wangmiao:~/lesson# vim web.c
root@wangmiao:~/lesson# gcc web.c -o webtwo
In file included from web.c:12:0:
wrap.h:6:44: error: unknown type name ‘socklent_t’
 void Bind(int fd,const struct sockaddr *sa,socklent_t salen);
                                            ^
root@wangmiao:~/lesson# vim wrap.h
root@wangmiao:~/lesson# gcc web.c -o webtwo
/tmp/ccSp36wf.o：在函数‘http_send’中：
web.c:(.text+0xc6)：对‘Write’未定义的引用
/tmp/ccSp36wf.o：在函数‘main’中：
web.c:(.text+0x14f)：对‘Socket’未定义的引用
web.c:(.text+0x1ee)：对‘Bind’未定义的引用
web.c:(.text+0x202)：对‘Listen’未定义的引用
web.c:(.text+0x235)：对‘Accept’未定义的引用
web.c:(.text+0x255)：对‘peeror’未定义的引用
web.c:(.text+0x278)：对‘Close’未定义的引用
web.c:(.text+0x297)：对‘Read’未定义的引用
web.c:(.text+0x357)：对‘Close’未定义的引用
web.c:(.text+0x36f)：对‘Close’未定义的引用
collect2: error: ld returned 1 exit status
root@wangmiao:~/lesson# gcc web.c wrap.c -o web
wrap.c: In function ‘Write’:
wrap.c:87:6: error: ‘error’ undeclared (first use in this function)
   if(error == EINTR)
      ^
wrap.c:87:6: note: each undeclared identifier is reported only once for each function it appears in
root@wangmiao:~/lesson# vim wrap.c
root@wangmiao:~/lesson# vim wrap.c
root@wangmiao:~/lesson# gcc web.c wrap.c -o web
/tmp/cc4QQlah.o：在函数‘main’中：
web.c:(.text+0x255)：对‘peeror’未定义的引用
/tmp/ccqcgrcT.o：在函数‘Accept’中：
wrap.c:(.text+0x65)：对‘perr_exit’未定义的引用
/tmp/ccqcgrcT.o：在函数‘Bind’中：
wrap.c:(.text+0x99)：对‘perr_exit’未定义的引用
/tmp/ccqcgrcT.o：在函数‘Connect’中：
wrap.c:(.text+0xca)：对‘perr_exit’未定义的引用
/tmp/ccqcgrcT.o：在函数‘Listen’中：
wrap.c:(.text+0xf4)：对‘perr_exit’未定义的引用
/tmp/ccqcgrcT.o：在函数‘Socket’中：
wrap.c:(.text+0x12a)：对‘perr_exit’未定义的引用
/tmp/ccqcgrcT.o:wrap.c:(.text+0x3c1): 跟着更多未定义的参考到 perr_exit
collect2: error: ld returned 1 exit status
root@wangmiao:~/lesson#

原本是想把文件拷贝到目录下的，
可是发现root的路径压根打不开，气的我吐血呀！
后来在网上搜索到了这个命令，sudo nautilus，
试了之后发现还是没有用
root@wangmiao:~/lesson# sudo nautilus
xnxy123
sudo：无法解析主机：wangmiao
No protocol specified

** (nautilus:3397): WARNING **: Could not open X display
No protocol specified
error: XDG_RUNTIME_DIR not set in the environment.

(nautilus:3397): Gtk-WARNING **: cannot open display: :0
root@wangmiao:~/lesson# xnxy123
xnxy123：未找到命令
root@wangmiao:~/lesson# sudo nautilus
xnxy123
sudo：无法解析主机：wangmiao
No protocol specified

** (nautilus:3409): WARNING **: Could not open X display
No protocol specified
error: XDG_RUNTIME_DIR not set in the environment.

(nautilus:3409): Gtk-WARNING **: cannot open display: :0
root@wangmiao:~/lesson# xnxy123
xnxy123：未找到命令
root@wangmiao:~/lesson#

我又进行了一波新的操作，试试！
Linux下 在root 用户下的文件夹如何复制到 另一个用户下 ？
首先
su root
然后
cp /root/文件夹 /home/用户名/文件夹
最后
chown -R 用户名:用户组 /home/用户名/文件夹
exit

**************************以下是web.c代码**********************************

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<ctype.h>
#include <signal.h>
#include<sys/wait.h>

#include "wrap.h"

#define BUFF_SIZE 1024
#define SERV_PORT 8000

void handle_sig(int sig)
{
 printf("child exit\n");
 wait(NULL);
}

char *http_res_tmpl = "HTTP/1.1 200 OK\r\n"
     "Server:Cleey's Server v1.0\r\n"
     "Accept-Ranges:bytes\r\n"
     "Content_Length:%d\r\n"
     "Connection:close\r\n"
     "Content-Type:%s\r\n\r\n";

void http_send(int sock_client,char *content)
{
 char HTTP_HEADER[BUFF_SIZE],HTTP_INFO[BUFF_SIZE];
 int len= strlen(content);
 sprintf(HTTP_HEADER,http_res_tmpl,len,"text/html");
 len = sprintf(HTTP_INFO,"%s%s",HTTP_HEADER,content);

 Write(sock_client,HTTP_INFO,len);
}

int main(void)
{
 struct sockaddr_in servaddr,cliaddr;
 socklen_t cliaddr_len;
 int listenfd,connfd;
 char buf[BUFF_SIZE];
 char str[INET_ADDRSTRLEN];
 int i,n;

 struct sigaction act;
 act.sa_handler = handle_sig;
 sigemptyset(&act.sa_mask);
 act.sa_flags = 0;
 sigaction(SIGCHLD,&act,NULL);

 listenfd = Socket(AF_INET,SOCK_STREAM,0);
 bzero(&servaddr,sizeof(servaddr));
 servaddr.sin_family = AF_INET;
 servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
 servaddr.sin_port = htons(SERV_PORT);

 int opt = 1;
 setsockopt(listenfd,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(opt));

 Bind(listenfd,(struct sockaddr *)&servaddr,sizeof(servaddr));
 Listen(listenfd,20);

 printf("Accepting connections../n");
 while(1)
 {
  cliaddr_len = sizeof(cliaddr);
  connfd = Accept(listenfd,(struct sockaddr *)&cliaddr,&cliaddr_len);
  
  n = fork();
  if(n ==-1 )
  {
   peeror("call to fork");
   exit(1);
  }else if(n == 0)
  {
   //child
   Close(listenfd);
   n = Read(connfd,buf,BUFF_SIZE);
   if(n == 0)
   {
    printf("the other side has been closed.\n");
    break;
   }
   printf("received from %s at PORT %d \n",inet_ntop(AF_INET,&cliaddr.sin_addr,str,sizeof(str)),ntohs(cliaddr.sin_port));
   fputs(buf,stdout);
   http_send(connfd,"hello world!");
   Close(connfd);
   exit(0);
  }else
  {
   //parent
   Close(connfd);
  }
 }
}

**************************以下是wrap.c代码**********************************

#include<stdlib.h>
#include<errno.h>
#include<sys/socket.h>
#include<unistd.h>
#include<stdio.h>

void peer_exit(const char *s)
{
 perror(s);
 exit(1); 
}

int Accept(int fd,struct sockaddr *sa,socklen_t *salenptr)
{
 int n;
again:
 if((n = accept(fd,sa,salenptr)) < 0)
 {
  if((errno == ECONNABORTED)||(errno == EINTR))
  {
   goto again;
  }else
  {
   perr_exit("accept error");
  }
 }
 return n;
}

void Bind (int fd,const struct sockaddr *sa,socklen_t salen)
{
 if(bind(fd,sa,salen)<0)
 {
  perr_exit("bind error");
 }
}

void Connect (int fd,const struct sockaddr *sa ,socklen_t salen)
{
 if(connect(fd,sa,salen) < 0)
 {
  perr_exit("connect error");
 }
}

void Listen(int fd,int backlog)
{
 if(listen(fd,backlog) < 0)
 {
  perr_exit("listen error");
 }
}

int Socket(int family, int type,int protocol)
{
 int n;
 if((n = socket(family,type,protocol)) < 0)
 {
  perr_exit("socket error");
 }
 return n;
}

ssize_t Read(int fd,void *ptr,size_t nbytes)
{
 ssize_t n;
again:
 if((n = read(fd,ptr,nbytes)) == -1)
 {
  if(errno == EINTR)
  {
   goto again;
  }else
  {
   return -1;
  }
 }
 return n ;
}

ssize_t Write (int fd,const void *ptr,size_t nbytes)
{
 ssize_t n;
again:
 if((n = write(fd,ptr,nbytes)) == -1)
 {
  if(errno == EINTR)
  {
   goto again;
  }else
  {
   return -1;
  }
 }
 return n;
}

ssize_t Readn(int fd,void *vptr,size_t n)
{
 size_t nleft;
 ssize_t nread;
 char *ptr;

 ptr = vptr;
 nleft = n;
 while(nleft >0)
 {
  if((nread = read(fd,ptr,nleft)) < 0)
  {
   if(errno == EINTR)
   {
    nread = 0;
   }else if( nread == 0)
   {
    break;
   }
  }
  
  nleft -= nread;
  ptr += nread;
 }
 return n - nleft;
}

ssize_t Writen(int fd,const void *vptr,size_t n)
{
 size_t nleft;
 ssize_t nwrittrn;
 const char *ptr;

 ptr = vptr;
 nleft = n;

 while(nleft > 0)
 {
  if((nwrittrn = write(fd,ptr,nleft)) <= 0)
  {
   if(nwrittrn < 0 && errno == EINTR)
   {
    nwrittrn = 0;
   }else
   {
    return -1;
   }
  }
  
  nleft -= nwrittrn;
  ptr += nwrittrn;
 }
 return n;
}

static ssize_t my_read(int fd,char *ptr)
{
 static int read_cnt;
 static char *read_ptr;
 static char read_buf[100];

 if(read_cnt <= 0)
 {
  again:
   if((read_cnt = read(fd,read_buf,sizeof(read_buf))) < 0)
   {
    if(errno == EINTR)
    {
     goto again;
    }
    return -1;
   }else if(read_cnt == 0)
   {
    return 0;
   }
   read_ptr = read_buf;
 }
 read_cnt --;
 *ptr = *read_ptr++;
 return 1;
}

ssize_t Readline(int fd,void *vptr,size_t maxlen)
{
 ssize_t n,rc;
 char c,*ptr;

 ptr = vptr;
 for(n = 0;n < maxlen;n++)
 {
  rc = my_read(fd,&c);
  if(rc == 1)
  {
   *ptr++ = c;
   if(c == '\n')
   {
    break;
   }
  }else if(rc == 0)
  {
   *ptr = 0;
   return n-1;
  }else
  {
   return -1;
  }
 }
 
 *ptr = 0;
 return n;
}

void Close(int fd)
{
 if(close(fd) == -1)
 {
  perr_exit("close error");
 }
}

**************************以下是wrap.h代码*********************************

#ifndef WRAP_H
#define WRAP_H

void perr_exit(const char *s);
int Accept(int fd,struct sockaddr *sa,socklen_t *salenptr);
void Bind(int fd,const struct sockaddr *sa,socklen_t salen);
void Connect(int fd,struct sockaddr *sa,socklen_t salen);
void Listen(int fd,int backlog);
int Socket(int family,int type,int protocol);
ssize_t Read(int fd,void *ptr,size_t nbytes);
ssize_t Write(int fd,void *ptr,size_t nbytes);
ssize_t Readn(int fd,void *vptr,size_t n);
ssize_t Writen(int fd,const void *vptr,size_t n);
ssize_t Readline(int fd,void *vptr,size_t maxlen);
void Close(int fd);

#endif