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POFake serial communication under Linux
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copied!<p>I have an application where I want to simulate the connection between a device and a "modem". The device will be connected to a serial port and will talk to the software modem through that.</p> <p>For testing purposes I want to be able to use a mock software device to test send and receive data.</p> <p>Example Python code</p> <pre><code>device = Device() modem = Modem() device.connect(modem) device.write("Hello") modem_reply = device.read() </code></pre> <p>Now, in my final app I will just pass /dev/ttyS1 or COM1 or whatever for the application to use. But how can I do this in software? I am running <strong>Linux</strong> and application is written in <strong>Python</strong>.</p> <p>I have tried making a FIFO (<code>mkfifo ~/my_fifo</code>) and that does work, but then I'll need one FIFO for writing and one for reading. What I want is to open <code>~/my_fake_serial_port</code> and read and write to that.</p> <p>I have also lpayed with the <code>pty</code>module, but can't get that to work either. I can get a master and slave file descriptor from <code>pty.openpty()</code> but trying to read or write to them only causes <code>IOError Bad File Descriptor</code> error message.</p> <h2>Update</h2> <p>Comments pointed me to the SO question <a href="https://stackoverflow.com/questions/2175440/are-there-some-program-like-com2com-in-linux">Are there some program like COM0COM in linux?</a> which uses <code>socat</code> to setup a virtual serial connection. I used it like this:</p> <p><code>socat PTY,link=$HOME/COM1 PTY,link=$HOME/COM2</code></p> <p>To the rest of you, thank you for giving me valuable information. I chose to accept <em>Vinay Sajips</em>'s answer since that is the solution which I went for before the socat suggestion showed up. It seems to work well enough.</p>

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