{"id":8642,"date":"2017-06-09T09:00:03","date_gmt":"2017-06-09T13:00:03","guid":{"rendered":"https:\/\/blogs.mathworks.com\/pick\/?p=8642"},"modified":"2017-06-08T01:33:04","modified_gmt":"2017-06-08T05:33:04","slug":"launch-and-manage-external-processes-from-matlab","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/pick\/2017\/06\/09\/launch-and-manage-external-processes-from-matlab\/","title":{"rendered":"Launch and manage external processes from MATLAB"},"content":{"rendered":"\r\n

Jiro<\/a>‘s pick this week is Process Manager<\/a> by Brian Lau<\/a>.<\/p>

With MATLAB being able to interface<\/a> with other languages and environments, I pretty much do everything from within MATLAB. One operation I do quite often is controlling Microsoft® applications via the COM interface<\/a>, such as composing and sending emails with Outlook® or opening and synchronizing two PowerPoint® documents.<\/p>

But even before COM interfaces, I used to just call out to the OS to run some executables, using the system<\/tt><\/a> or the dos<\/tt><\/a> command.<\/p>

Brian’s processManager<\/tt> is the system<\/tt> command on steroids. Imagine that you want to run a program in the background, and you would like to be able to check on the status or get notified when things are done. processManager<\/tt> gives you that power.<\/p>

As an example, I will use the “ping”<\/a> command that would ping a host name 15 times. This command, when run from the OS console, will test the reachability of a host multiple times and echo the response.<\/p>

tic                         % capture the start time<\/span>\r\np = processManager('command'<\/span>,'ping -n 15 www.mathworks.com'<\/span>);\r\npause(3)                    % pause for 3 seconds<\/span>\r\n<\/pre>
ms-www.mathworks.com [144.212.244.17]に ping を送信しています 32 バイトのデータ:\r\n144.212.244.17 からの応答: バイト数 =32 時間 =173ms TTL=241\r\n144.212.244.17 からの応答: バイト数 =32 時間 =179ms TTL=241\r\n144.212.244.17 からの応答: バイト数 =32 時間 =174ms TTL=241\r\n<\/pre>
We can see that it’s now running. (I’m running this on a Japanese OS, hence the Japanese text)<\/p>
Let’s just let it run in the background and turn off the display.<\/p>
p.printStdout = false;      % turn off printing of stdout<\/span>\r\npause(3)                    % pause for 3 seconds<\/span>\r\n<\/pre>
We can periodically check to see that the process is still running.<\/p>
p.check                     % check the status of the process<\/span>\r\npause(3)                    % pause for 3 seconds<\/span>\r\n<\/pre>
Process  is still running.\r\n<\/pre>
It’s been a while. Let’s see if we’re still reaching the host.<\/p>
p.printStdout = true;       % turn on printing of stdout<\/span>\r\npause(3)                    % pause for 3 seconds<\/span>\r\n<\/pre>
144.212.244.17 からの応答: バイト数 =32 時間 =183ms TTL=241\r\n144.212.244.17 からの応答: バイト数 =32 時間 =175ms TTL=241\r\n144.212.244.17 からの応答: バイト数 =32 時間 =181ms TTL=241\r\n<\/pre>
Okay, just let me know when it’s done and tell me how long it took.<\/p>
p.printStdout = false;      % turn off printing of stdout<\/span>\r\naddlistener(p.state,'exit'<\/span>,@(o,e) disp(['Done. Elapsed time: '<\/span> num2str(toc) ' seconds'<\/span>]));\r\npause(5)                    % pause for 5 seconds<\/span>\r\n<\/pre>
Done. Elapsed time: 14.3583 seconds\r\n<\/pre>
There are other nice features, including the ability to<\/p>