I have a device that comes up as ttyACM0, however every time it is reset it iterates, so next time it will come up as ttyACM1 etc. Where might this lock be located so that I can remove it?
I'd like the device to come up as ttyACM0 repeatedly and only a second device show as ttyACM1.

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    When this happens, is there still a /dev/ttyACM0 device? And if so, does some process have it open? (use lsof to find out). – Mark Plotnick Feb 16 '15 at 14:59
  • Hi @MarkPlotnick There is always a device as the system is using a static device table, I have added multiple ACM interfaces to it. – Paul Feb 16 '15 at 15:57

You cannot do exactly what you want -- force the device to register as ttyACM0 -- however, you can set up a udev rule to create a symlink, associated with a specific device, so that regardless of whether it registers as ttyACM0 or ttyACM1, the specified symlink (e.g., /dev/my_ttyACM) will be available to access it.

The reason you can't force ttyACM0 instead of ttyACM1 is that this is selected by the kernel and cannot/should not be renamed.

  • Hi, I 'll try that out cheers, sounds good! As I am using a static device table I just have to see how often the device resets, because if this happens hundreds of times it will be a nightmare to add all those to a static device table? Anyway will have a look thank you! – Paul Feb 16 '15 at 15:59

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