bash 无法写入命名管道
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Can't write to named pipe
提问by tay10r
I'm trying to write to a named pipe, made with mkfifo. But when I run the command, (ex) ls > myNamedPipe, I can no longer enter commands into the bash. I can still write characters and that's pretty much it.
我正在尝试写入使用mkfifo制作的命名管道。但是当我运行命令 (ex) 时ls > myNamedPipe，我无法再将命令输入到 bash 中。我仍然可以写字符，仅此而已。
回答by michaelmeyer
A named pipe remains opened until you read it from some other place. This is to permit communication between different processes.
命名管道保持打开状态，直到您从其他地方读取它。这是为了允许不同进程之间的通信。
Try:
尝试：
mkfifo fifo
echo "foo" > fifo
Then open another terminal and type:
然后打开另一个终端并输入：
cat fifo
If you return to you first terminal, you'll notice that you can now enter other commands.
如果您返回到第一个终端，您会注意到现在可以输入其他命令。
See also what happends with the reverse :
另请参阅相反的情况：
# terminal 1
cat fifo
# terminal 2
echo "foo" > fifo
# and now you can see "foo" on terminal 1
If you want you terminal not to "hang on" when trying to write something to the fifo, attach to the fifo a file descriptor :
如果您希望终端在尝试向 fifo 写入内容时不要“挂起”，请将文件描述符附加到 fifo：
mkfifo fifo
exec 3<> fifo
echo "foo" > fifo
echo "bar" > fifo
