device /dev/ttyusb0 lock failed: operation not permitted

Question

I was playing around with a router earlier this evening using minicom and I must not have closed it cleanly. Here is the error message that I get when I try to open minicom:

device /dev/ttyusb0 lock failed: operation not permitted

I have two questions, 1) how would I go about getting out of this state, and 2) how do I exit minicom cleanly so that I can avoid this happening again.

score 25 · Accepted Answer · edited Jan 09 '13 at 17:00

25

I found I was able to fix the situation on my CentOS box by running minicom -S <device> -o and the do the normal exit key sequence (CTRL-a, x).

In your situation it would have been

sudo minicom -S ttyusb0 -o

This cleared the lock files minicom had placed in /var/lock/

Good luck Ash

edited Jan 09 '13 at 17:00

benmarks

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answered Nov 01 '12 at 04:05

Ash

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"This cleared the lock files..." This didn't work, but manually deleting these lock files did. heh. – xtian Dec 26 '13 at 23:31
I manually deleted the `/var/lock/LCK..ttyUSB0` file and it works now. – smwikipedia Oct 19 '21 at 00:50

score 8 · Answer 2 · answered Oct 05 '17 at 13:42

I ran into a similar issue with using gtkterm from a remote terminal. I had shutdown the terminal without explicitly terminating gtkterm. The result was that subsequent gtkterm sessions gave me the error:

Device /dev/ttyUSB0 is locked.

Checking the process list via ps did not show any gtkterm processes still running.

I corrected this by simply deleting /run/lock/LCK..ttyUSB0. After doing that, gtkterm was able to open ttyUSB0 successfully.

score 3 · Answer 3 · answered Aug 09 '18 at 03:21

[root@edge-tc lock]# minicom'
Device /dev/ttyUSB0 lock failed: Operation not permitted.'
Solution:'
Check the process which have locked and kill the process'
[root@edge-tc lock]# fuser /dev/ttyUSB0'
/dev/ttyUSB0: 18328
[root@edge-tc lock]# kill -9 18328
[root@edge-tc lock]#'
[root@edge-tc lock]#'
[root@edge-tc lock]# minicom'
Welcome to minicom 2.1'

score 0 · Answer 4 · answered Aug 05 '19 at 14:01

The canonical way is to use lockdev. This manages the lock files on a per-device basis in /run/lock/lockdev/ (at least under CentOS 7.x).

lockdev <device> can be used without being root, and returns non-zero if the device has already been locked, in which case it can be unlocked with lockdev -u <device>.

This is apparently obsolete these days, but minicom (at least as of version 2.6.2) still uses it.

device /dev/ttyusb0 lock failed: operation not permitted

4 Answers4