sem_open() 错误：Linux 上的“未定义对 sem_open() 的引用”（Ubuntu 10.10）
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sem_open() error: "undefined reference to sem_open()" on linux (Ubuntu 10.10)
提问by Robin
So I am getting the error: "undefined reference to sem_open()" even though I have include the semaphore.h header. The same thing is happening for all my pthread function calls (mutex, pthread_create, etc). Any thoughts? I am using the following command to compile:
所以我收到错误：“未定义对 sem_open() 的引用”，即使我已经包含了 semaphore.h 标头。我所有的 pthread 函数调用（互斥锁、pthread_create 等）都发生了同样的事情。有什么想法吗？我正在使用以下命令进行编译：
g++ '/home/robin/Desktop/main.cpp' -o '/home/robin/Desktop/main.out'
g++ '/home/robin/Desktop/main.cpp' -o '/home/robin/Desktop/main.out'
#include <iostream>
using namespace std;
#include <pthread.h>
#include <semaphore.h>
#include <fcntl.h>
const char *serverControl = "/serverControl";
sem_t* semID;
int main ( int argc, char *argv[] )
{
//create semaphore used to control servers
semID = sem_open(serverControl,O_CREAT,O_RDWR,0);
return 0;
}
采纳答案by Vlad H
You need link with pthread lib, using -lpthreadoption.
您需要使用-lpthread选项与 pthread 库链接。
回答by William Pursell
Including the header does not tell ld about the library. You need to add -lrt to your compilation command line. For threading, you need either -lpthread or -pthread, depending on your platform.
包含标题不会告诉 ld 有关库的信息。您需要将 -lrt 添加到编译命令行。对于线程，您需要 -lpthread 或 -pthread，具体取决于您的平台。
The library is not the header. The header is not the library. This is an important distinction. See What's the difference between a header file and a library?
图书馆不是标题。标题不是库。这是一个重要的区别。请参阅头文件和库之间的区别是什么？
回答by Sanjay Bhosale
The working option in Ubuntu is -lpthread. But if you work on suse or other systems the correct option is -lrt. Also the book Linux Programmin Interfacementions -lrtas the correct option.
Ubuntu 中的工作选项是-lpthread。但是，如果您在 suse 或其他系统上工作，则正确的选项是-lrt。此外，Linux Programmin Interface一书提到-lrt作为正确选项。
