Check whether a license is available.

For testing we run as many matlab instances as possible.

How can we find out that no license is available?

At best without starting matlab.

But if we have to start matlab: what is a save way to check whether a license is available or not?

Answer 1

[Walter Roberson]

Once you are in MATLAB, to check whether a toolbox license is available, you can use license('test') . For example,

license('test', 'Symbolic_Toolbox')

ans = 1

The names you have to use are not always obvious; I listed as many names as I could find in https://www.mathworks.com/matlabcentral/answers/449314-how-do-features-from-license-correspond-to-names-from-ver?s_tid=srchtitle

If you are using a license manager, then you can look at license usage using lmutil with the lmstats command or possibly using a GUI; see https://sites.math.washington.edu/~reu/codes/Matlab/Matlab%201/jhelp/base/install/pc/ch3_li12.html

[Ernst Reissner]

Ah i see... but if I want to test just the matlab interpreter?

Does this mean that matlab can always be started and the function license('test') can always be invoked, and to check I just have to use

license('test', 'MATLAB')

?

[Walter Roberson]

If I recall correctly MATLAB will quit immediately if you run out of licenses, so for your purposes you will probably need the lmstat approach

[Ernst Reissner]

Someone removed my answer to the original answer of Walter Robertson.

This is not helpful.

If there is a list of names of licenses and MATLAB is among them,

and if one may invoke

license('test', 'MATLAB')

and if matlab quits if running out of licenses,

then if a result is given at all, this is always 1, right?

I know that there are installations not using lmutil.

This would be important.

[Walter Roberson]

I think your comment is still at https://www.mathworks.com/matlabcentral/answers/1763205-check-whether-a-license-is-available#comment_2277655 ? You might need to "Show older comments" to see it.

You cannot use the license() command to test for a MATLAB license until after you have started MATLAB, but you cannot start MATLAB unless there is an available license.

The lmutil lmstat is a utility that is not part of MATLAB, but which can talk to the license server to find out licenses in use. It will not tell you directly how many licenses are available -- you have to look at the line such as

Users of MATLAB: (Total of 5 licenses available)

If you are using Standalone Named User licenses (license resides on host, no license server) and the processes are all being launched by the same username, then it is not clear to me whether the limit applies. In such a situation you could potentially find out how many are already executing using taskmgr (Windows) or ps (MacOS or Linux)