Linux 檔案操作中的阻塞和非阻塞操作

轉：http://blog.sina.com.cn/s/blog_5f84dc840100n2hb.html//原始碼#include <stdio.h>#include <unistd.h>#include <fcntl.h>#include <stdlib.h>#include <errno.h>char buffer[4096];int main(int argc,char **argv){    int delay = 1, n, m = 0;        if(argc > 1)    {        delay = atoi(argv[1]);        printf("delay = %d seconds\n", delay);    }    fcntl(0,F_SETFL,fcntl(0,F_GETFL)|O_NONBLOCK);//stdin    fcntl(1,F_SETFL,fcntl(1,F_GETFL)|O_NONBLOCK);//stdout        while(1)    {        n = read(0,buffer,4096);        if (n > 0)        {            printf("Got %d byte data.\n", n);        }        if (n>0)            m = write (1,buffer,n);        if ((n<0||m<0) && (errno != EAGAIN))            break;        if ((n<0||m<0) && (errno == EAGAIN))        {           perror( n<0 ? "stdin working in NONBLOCK, no data!" : "stdout working in NONBLOCK, no data");        }        sleep(delay);    }    perror( n<0 ? "stdin" : "stdout");    exit(1);}執行：[root@localhost nbtest]# ./nbtest 5delay = 5 secondsstdin working in NONBLOCK, no data!: Resource temporarily unavailable12345Got 6 byte data.12345注意，（1）在標準輸入中鍵入斷行符號後才算是有效輸入。（2）斷行符號也算是輸入的一個字元，比如輸入12345+斷行符號，實際讀入的長度是6個位元組。