在Linux下防止某个程序被运行两次的方法

;通过文件锁来实现,在程序运行的一开始,检查某文件是否存在,如果存在则说明改程序已经在运行了,如果不存在则利用open语句创建该文件,程序退出时关闭并删除此文件 。static char file_lock[sizeof(ctl_addr.sun_path)] = /var/run/file.pid;static bool file_lock_created = FALSE;static intcreate_lock(void){ int fd = open(file_lock, O_WRONLY | O_CREAT | O_EXCL | O_TRUNC, S_IRUSR | S_IRGRP | S_IROTH); if (fd < 0) { if (errno == EEXIST) { fprintf(stderr, "file: lock file "%s" already existsn", file_lock); exit_file(10); } else { fprintf(stderr, "file: unable to create lock file "%s" (%d %s)n" , file_lock, errno, strerror(errno)); exit_file(1); } } file_lock_created = TRUE; return fd;}static boolfill_lock(int lockfd){ char buf[30]; /* holds "n" */ pid_t pid; int len; pid = getpid(); len = snprintf(buf, sizeof(buf), "\un", (unsigned int) pid); bool ok = len > 0 && write(lockfd, buf, len) == len; close(lockfd); return ok;}static voiddelete_lock(void){ if (file_lock_created) { //delete_ctl_socket(); unlink(file_lock); /* is noting failure useful? */ }}

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