If your applications are only on Windows platform, you can try using .net objects.
The SendWait method of the SendKeys objects allows to send virtually any key, or key combination, to the application which has the focus, including the "modifier" keys like Alt, Shift, Ctrl etc ...
The first thing to do is to import the .net library, then the full syntax to send the ENTER key would be:
NET.addAssembly('System.Windows.Forms');
System.Windows.Forms.SendKeys.SendWait('{ENTER}'); %// send the key "ENTER"
If you only do it once the full syntax is OK. If you plan to make extensive use of the command, you can help yourself with an anonymous helper function.
A little example with notepad
%% // import the .NET assembly and define helper function
NET.addAssembly('System.Windows.Forms');
sendkey = @(strkey) System.Windows.Forms.SendKeys.SendWait(strkey) ;
%% // prepare a few things to send to the notepad
str1 = 'Hello World' ;
str2 = 'OMG ... my notepad is alive' ;
file2save = [pwd '\SelfSaveTest.txt'] ;
if exist(file2save,'file')==2 ; delete(file2save) ; end %// this is just in case you run the test multiple times.
%% // go for it
%// write a few things, save the file then close it.
system('notepad &') ; %// Start notepad, without matlab waiting for the return value
sendkey(str1) %// send a full string to the notepad
sendkey('{ENTER}'); %// send the {ENTER} key
sendkey(str2) %// send another full string to the notepad
sendkey('{! 3}'); %// note how you can REPEAT a key send instruction
sendkey('%(FA)'); %// Send key combination to open the "save as..." dialog
pause(1) %// little pause to make sure your hard drive is ready before continuing
sendkey(file2save); %// Send the name (full path) of the file to save to the dialog
sendkey('{ENTER}'); %// validate
pause(3) %// just wait a bit so you can see you file is now saved (check the titlebar of the notepad)
sendkey('%(FX)'); %// Bye bye ... close the Notepad
As explained in the Microsoft documentation the SendKeys class may have some timing issues sometimes so if you want to do complex manipulations (like Tab multiple times to change the button you actually want to press), you may have to introduce a pause in your Matlab calls to SendKeys.
Try without first, but don't forget you are managing a process from another without any synchronization between them, so timing all that can require a bit of trial and error before you get it right, at least for complex sequences (simple one should be straightforward).
In my case above for example I am running all my data from an external hard drive with an ECO function which puts it into standby, so when I called the "save as..." dialog, it takes time for it to display because the HDD has to wake up. If I didn't introduce the pause(1), sometimes the file path would be imcomplete (the first part of the path was send before the dialog had the focus).
Also, do not forget the & character when you execute the external program. All credit to Luis Mendo for highlighting it. (I tend to forget how important it is because I use it by default. I only omit it if I have to specifically wait for a return value from the program, otherwise I let it run on its own)
The special characters have a special code. Here are a few:
Shift +
Control (Ctrl) ^
Alt %
Tab {TAB}
Backspace {BACKSPACE}, {BS}, or {BKSP}
Validation {ENTER} or ~ (a tilde)
Ins Or Insert {INSERT} or {INS}
Delete {DELETE} or {DEL}
Text Navigation {HOME} {END} {PGDN} {PGUP}
Arrow Keys {UP} {RIGHT} {DOWN} {LEFT}
Escape {ESC}
Function Keys {F1} ... {F16}
Print Screen {PRTSC}
Break {BREAK}
The full list from Microsoft can be found here
