For a particle physics project (micrOMEGAs), I have had to unpack a .tgz, and then run "make" in it (following this tutorial https://lapth.cnrs.fr/micromegas/).

I first unpacked using:

tar -zxvf micromegas_4.3.4.tgz

Then I obtained a folder micromegas_4.3.4, in which I ran make:

cd micromegas_4.3_4

At the end of the process, the terminal is available for next instructions, but in its last message mentions:

'../lib/micromegas.a' seems to have been created in deterministic mode. 
'limits.o' will always be updated. 
Please consider passing the U flag to ar to avoid the problem.

How do I fix this (supposedly using non-deterministic mode?)?

There are next steps to this installation process, but for the moment I just wanted to make sure that my folder micromegas_4.3.4 has been accurately compiled using make, and if not, what other packages/auxiliary files would I need to add to my Ubuntu platform.

Fundamentally, I am just compiling the contents of an unpacked folder. Then this is supposed to be ready to use using the command line (no GUI involved), for physical calculations.

(This is Ubuntu 17.04 running on a VirtualBox in Windows 10 by the way.)

  • Could you please add a little more detail? What exactly did you do, what did you want to achieve and what happened instead? Did you encounter any warning or error messages? Please reproduce them in their entirety in your question. You can select, copy and paste terminal content and most dialogue messages in Ubuntu. (see How do I ask a good question?) Jun 14, 2017 at 21:52
  • I have expanded a bit on my post and its context, and provided the link to the specific setup I am supposed to follow, if that is of any help.
    – N.E.
    Jun 14, 2017 at 23:19

2 Answers 2


The message from ar is a notice about the build process not an error message. As far as I understand it, it means that rebuilding the software after modification may take longer than necessary; nothing to worry about.

  • Understood. What about the deterministic mode? Is that a cause for concern? Because I do get problems in the ulterior parts to my coding (not mentioned in my original post) and was trying to rewind back to where I could have made any mistake(s).
    – N.E.
    Jun 15, 2017 at 5:56
  • @N.E.: I suggest you look up "deterministic" in the ar(1) manual. Jun 15, 2017 at 8:49
  • Apologies but I'm quite new to Ubuntu, and can't seem to figure out, in the manual you just showed me, where and if I can perform such a thing as pass the U flag to ar.
    – N.E.
    Jun 15, 2017 at 12:08
  • Could you please open a new question if you have a new or follow-up question? The comment section is not suitable or meant for new questions or extended discussion. You’re welcome to send me a comment with a notification to draw my attention to it. Thanks. Jun 15, 2017 at 16:54

The problem is due to change in the behavior of the ar command, which is now configured with --enable-deterministic-archives (see here and here).

A possible solution is to redefine the global variable for ar flags to disable deterministic archives with the U option. In the console before the make command, set

export ARFLAGS=rvU

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