 <p>There is no difference in reading standard input from threads except if more than one thread is trying to read it at the same time. Most likely your threads are not all calling functions to read standard input all the time, though.</p> <p>If you regularly need to read input from the user you might want to have one thread that just reads this input and then sets flags or posts events to other threads based on this input.</p> <p>If the kill character is the only thing you want or if this is just going to be used for debugging then what you probably want to do is occasionally poll for new data on standard input. You can do this either by setting up standard input as non-blocking and try to read from it occasionally. If reads return 0 characters read then no keys were pressed. This method has some problems, though. I've never used <em>stdio.h</em> functions on a <code>FILE *</code> after having set the underlying file descriptor (an int) to non-blocking, but suspect that they may act odd. You could avoid the use of the <em>stdio</em> functions and use <code>read</code> to avoid this. There is still an issue I read about once where the block/non-block flag could be changed by another process if you forked and exec-ed a new program that had access to a version of that file descriptor. I'm not sure if this is a problem on all systems. Nonblocking mode can be set or cleared with a 'fcntl' call.</p> <p>But you could use one of the polling functions with a very small (0) timeout to see if there is data ready. The <code>poll</code> system call is probably the simplest, but there is also <code>select</code>. Various operating systems have other polling functions.</p> <pre><code>#include &lt;poll.h&gt; ... /* return 0 if no data is available on stdin. &gt; 0 if there is data ready &lt; 0 if there is an error */ int poll_stdin(void) { struct pollfd pfd = { .fd = 0, .events = POLLIN }; /* Since we only ask for POLLIN we assume that that was the only thing that * the kernel would have put in pfd.revents */ return = poll(&amp;pfd, 1, 0); } </code></pre> <p>You can call this function within one of your threads until and as long as it retuns 0 you just keep on going. When it returns a positive number then you need to read a character from stdin to see what that was. Note that if you are using the <em>stdio</em> functions on <code>stdin</code> elsewhere there could actually be other characters already buffered up in front of the new character. <code>poll</code> tells you that the operating system has something new for you, not what C's <em>stdio</em> has.</p> <p>If you are regularly reading from standard input in other threads then things just get messy. I'm assuming you aren't doing that (because if you are and it works correctly you probably wouldn't be asking this question).</p>