如何（完全）更改GCC目录搜索路径？

Question

OK所以这里是我试图编译代码：

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


#define MAX_BUFFER 1024 

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


int main(int argc, char **argv) 
{ 

    int connector,flags,r; 
    u_int port; 
    struct hostent*  host; 
    struct in_addr   in; 
    struct sockaddr_in  rmaddr; 
    struct sctp_initmsg initmsg; 
    struct sctp_sndrcvinfo sinfo; 
    struct sctp_event_subscribe events; 
    bool connected = false; 
    char buffer[MAX_BUFFER]; 
    char* exit = "quit"; 

    if(argc!=2) { 
     printf("Usage: %s ipaddress\n", argv[0]); 
    return -1; 
    } 



    if((connector = socket(AF_INET,SOCK_STREAM, IPPROTO_SCTP))<0){ 
     perror("socket"); 
     return -1; 
    } 



    printf("Enter the port number you wish to connect(on): "); 
    scanf("%u", &port); 
    printf("\n"); 

    if(port==0){ 
       printf("ERR0R: Port number must be between 1 & 65,535\n"); 
       printf("\n"); 
       printf("Enter the port number you wish to connect(on): "); 
       scanf("%u", &port); 
       printf("\n");   
    } 


    memset(&initmsg, 0, sizeof(initmsg)); 
    initmsg.sinit_num_ostreams = 3; 
    initmsg.sinit_max_instreams = 3; 
    initmsg.sinit_max_attempts = 2; 
    if(setsockopt(connector,IPPROTO_SCTP,SCTP_INITMSG,&initmsg,sizeof(initmsg))<0){ 
     perror("setsockopt"); 
     return -1; 
    } 

    bzero((void *)&rmaddr, sizeof(rmaddr)); 
    rmaddr.sin_family = AF_INET; 
    inet_pton(AF_INET, argv[1], &rmaddr.sin_addr); 
    rmaddr.sin_port = htons(port); 



    connect(connector,(struct sockaddr*)&rmaddr,sizeof(rmaddr)); 

     connected=true; 
     memset((void *)&events, 0, sizeof(events)); 
     events.sctp_data_io_event = 1; 
     setsockopt(connector, SOL_SCTP, SCTP_EVENTS,(const void *)&events, sizeof(events)); 
     printf("\n"); 
     printf("Connected to host: %s",argv[1],"on port %u",port); 
     printf("  type 'quit' to disconnect\n"); 
     printf("\n"); 



    while(connected==true){ 

     int nbs; 
     int nbr = 0; 
     int flags = MSG_NOSIGNAL; 
     printf(">"); 
     scanf("%s",buffer); 
     printf("\n"); 

     sinfo.sinfo_flags = flags; 

     nbs = send(connector,(void*)&buffer,sizeof(buffer),flags);   



     printf("\n"); 
     printf("# bytes sent %i\n", nbs); 
     printf("\n"); 

     if(nbs<0){ 
     perror("sendmsg"); 
      close(connector); 
      return -1; 
     } 

     while(nbr < nbs){ 
     socklen_t len = sizeof(rmaddr); 
     nbr = recv(connector,(void*)&buffer,sizeof(buffer),flags); 


     if(nbr<0){ 
       perror("recvmsg"); 
       close(connector); 
       return -1; 
     }else{ 
      printf(">>"); 
       printf("%s\n",buffer); 
       printf("\n"); 
     } 

     } 

    } 

}

当我输入命令 “gcc的sctp_ec.c” 我得到以下输出：

-*- mode: compilation; default-directory: "/usr/lib/gcc/x86_64-linux-gnu/4.8.4/include/" -*- 
Compilation started at Sun Aug 27 12:43:50 

gcc sctp_ec.c 
In file included from sctp_ec.c:10:0: 
/usr/include/net/sctp.h:55:22: fatal error: net/ipv6.h: No such file or directory 
compilation terminated. 

Compilation exited abnormally with code 1 at Sun Aug 27 12:43:50 

所以我知道问题是什么。 GCC编译器正在错误的目录中搜索！我希望它搜索路径中的文件：/usr/lib/gcc/x86_64-linux-gnu/4.8.4/include而不是/ usr/include。我尝试使用-I，-Idir和-isystem命令，但无济于事。使用-isystem在这两个路径中搜索，并且存在定义冲突。那么，我在这里做什么来永久地改变GCC/emacs24程序，以便在.c代码文件所在的第一个路径中搜索只有？

FTR我在Linux Mint的18.1运行emacs24和GCC。

Answer 1

如果设置环境变量C_INCLUDE_PATH到你想要的搜索路径的目录列表，这将是永久性的（设置在.profile或.login文件，取决于你的shell）。该值应该是您想要搜索的以冒号分隔的目录列表。

Answer 2

使用这些命令行选项之一：

> -I dir 
> -iquote dir 
> -isystem dir 
> -idirafter dir 

如果你真的需要改变搜索顺序的系统目录，使用-nostdinc和/或-isystem选项。