linux pid文件

linux使用pid file 

UNIX环境编程里面，讲了如何使用pid文件，但是比较隐晦，今天整理一下：

原文如下：

#include stdio.h #include stdlib.h #include string.h #include unistd.h #include sys/types.h #include sys/stat.h #include errno.h #include fcntl.h #define PIDFILE deamon.pid #define write_lock(fd,offset,whence,len) lock_reg(fd,F_SETLK,F_WRLCK,offset,whence,len)int lock_reg(int fd, int cmd, int type, off_t offset, int whence, off_t len){ flock lock; lock.l_type = type; // F_RDLCK, F_WRLCK, F_UNLCK lock.l_start = offset; // type offset, relative to l_whence lock.l_whence = whence; // SEEK_SET, SEEK_CUR, SEEK_END lock.l_len = len; return (fcntl(fd, cmd, lock));// -rw-r--r-- // 644#define FILE_MODE S_IRUSR|S_IWUSR|S_IRGRP|S_IROTHint main(int argc, char** argv){ int fd; if((fd = open(PIDFILE, O_WRONLY | O_CREAT, FILE_MODE)) 0){ printf( open file error!  exit(errno); if(lock_reg(fd, 0, SEEK_SET, 0) 0){ if(errno == EACCES || errno == EAGAIN){ printf( deamon is already running!\n  exit(0); else{ printf( write lock error!\n  exit(errno); if(ftruncate(fd, 0) 0){ printf( trancate error!\n  exit(errno); char buf[11]; snprintf(buf, sizeof(buf), %d , getpid()); if(write(fd, buf, strlen(buf)) != strlen(buf)){ printf( write our pid error!\n  exit(errno); int val; if((val = fcntl(fd, F_GETFD, 0)) 0){ printf( fnctl F_GETFD error!\n  exit(errno); val |= FD_CLOEXEC; if(fcntl(fd, F_SETFD, val) 0){ printf( fcntl F_SETFD error!\n  exit(errno); sleep(3); printf( exit!  exit(0);

直接调用如下：

#include stdio.h #include stdlib.h #include string.h #include unistd.h #include sys/types.h #include sys/stat.h #include errno.h #include fcntl.h int main(int argc, char** argv){ int fd; // -rw-r--r--  // 644 int mode = S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH; const char* file_name = deamon.pid  // open pid file if((fd = open(file_name, O_WRONLY | O_CREAT, mode)) 0){ printf( open file error!  exit(errno); // require write lock flock lock; lock.l_type = F_WRLCK; // F_RDLCK, F_WRLCK, F_UNLCK lock.l_start = 0; // type offset, relative to l_whence lock.l_whence = SEEK_SET; // SEEK_SET, SEEK_CUR, SEEK_END lock.l_len = 0; if(fcntl(fd, F_SETLK, lock) 0){ if(errno == EACCES || errno == EAGAIN){ printf( deamon is already running!\n  exit(0); else{ printf( write lock error!\n  exit(errno); // truncate file if(ftruncate(fd, 0) 0){ printf( trancate error!\n  exit(errno); // write the pid char buf[11]; snprintf(buf, sizeof(buf), %d , getpid()); if(write(fd, buf, strlen(buf)) != strlen(buf)){ printf( write our pid error!\n  exit(errno); // auto close when fork child process. int val; if((val = fcntl(fd, F_GETFD, 0)) 0){ printf( fnctl F_GETFD error!\n  exit(errno); val |= FD_CLOEXEC; if(fcntl(fd, F_SETFD, val) 0){ printf( fcntl F_SETFD error!\n  exit(errno); sleep(3); printf( exit!  exit(0);

: @myairen1365:哈哈，转眼间，这个我都写了三个年头了。换了两个镇江公司。从事了一个行业。

: @czc1009:呵呵，wireshark其实是能解rtmp的，端口1935，过滤为rtmpt就可以...

: 包解析部分清楚明白，要是能贴出wireshark的图就更好了，不过解析第14行错了吧，应该还是cli...

: @wei_bub:暂时公司没有考虑开源，产品还在研发中，估计以后稳定了把rtmp解析的库开源是有可能...

: 博主写的不错，挺清晰的，想问一下现在这套c++的是开源的么？我现在正在研究这方面的东西