If I type myprogram > file I end up with a file of size 0 except for one time when it worked. Same program, no changes between times when it worked and when it didn't. Without the redirection it prints out to the terminal just fine. Virtually all the online help assumes you are needing to redirect std error but that is not the case here.
如果我输入myprogram> file，我最终会得到一个大小为0的文件，除非它有效。相同的程序，它工作的时间和没有的时间之间没有变化。没有重定向，它打印到终端就好了。实际上所有的在线帮助都假定您需要重定向std错误，但这不是这种情况。
The program is multi threaded and reads a USB port and writes it out to a bluetooth port. There is not keyboard input and no exit, it just runs. I stop it with ctrl-c. This is embedded code on a headless linux Intel Edison.
该程序是多线程的，读取USB端口并将其写入蓝牙端口。没有键盘输入也没有退出，它只是运行。我用ctrl-c来阻止它。这是无头linux英特尔爱迪生的嵌入式代码。
I assume I need to do something in the code to allow for the redirection. It is probably something simple I should know but I don't. I would appreciate some help.
我假设我需要在代码中做一些事情以允许重定向。这可能是我应该知道的简单但我没有。我会感激一些帮助。
1 个解决方案
#1
2
When you redirect to a file, libc will automatically buffer your data.
当您重定向到文件时，libc将自动缓冲您的数据。
Since you kill your script instead of exiting gracefully, you stop the process before it writes the buffer out.
由于您终止了脚本而不是正常退出，因此在将缓冲区写出之前停止该过程。
You can use fflush(stdout); to write out (aka flush) the current buffer at any time.
你可以使用fflush（stdout）;随时写出（也就是刷新）当前缓冲区。
You can use setvbuf(stdout, NULL, _IONBF, 0); to disable stdout buffering all together.
你可以使用setvbuf（stdout，NULL，_IONBF，0）;一起禁用stdout缓冲。
#1
2
When you redirect to a file, libc will automatically buffer your data.
当您重定向到文件时，libc将自动缓冲您的数据。
Since you kill your script instead of exiting gracefully, you stop the process before it writes the buffer out.
由于您终止了脚本而不是正常退出，因此在将缓冲区写出之前停止该过程。
You can use fflush(stdout); to write out (aka flush) the current buffer at any time.
你可以使用fflush（stdout）;随时写出（也就是刷新）当前缓冲区。
You can use setvbuf(stdout, NULL, _IONBF, 0); to disable stdout buffering all together.
你可以使用setvbuf（stdout，NULL，_IONBF，0）;一起禁用stdout缓冲。