Results 1 to 3 of 3

Thread: open (/dev/ttyUSB0): Permission denied : Line in use

  1. #1
    Join Date
    Sep 2006
    Beans
    7,291
    Distro
    Lubuntu Development Release

    open (/dev/ttyUSB0): Permission denied : Line in use

    I'm trying to open a serial connection and get the following error when I try to connect either through my own account or via root using sudo:

    Code:
    cu -s 19200 -l /dev/ttyUSB0
    cu: open (/dev/ttyUSB0): Permission denied
    cu: /dev/ttyUSB0: Line in use
    I am a member of the group 'dialout'

    Code:
    ls -lh /dev/ttyUSB0 
    crw-rw---- 1 root dialout 188, 0 Jun 24 13:15 /dev/ttyUSB0
    What step am I missing?
    Last edited by Lars Noodén; June 25th, 2013 at 03:16 PM. Reason: there is no other way to change it to "solved"

  2. #2
    Join Date
    Nov 2006
    Location
    Belgium
    Beans
    3,008
    Distro
    Ubuntu 10.04 Lucid Lynx

    Re: open (/dev/ttyUSB0): Permission denied : Line in use

    what I gather from http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=264626 and https://bugzilla.redhat.com/show_bug.cgi?id=145459
    is that cu drops privileges to uucp:uucp and your serial port device must be rw for both that user and that group. Or something similar with unusual/unexpected permission requirements.

  3. #3
    Join Date
    Sep 2006
    Beans
    7,291
    Distro
    Lubuntu Development Release

    Re: open (/dev/ttyUSB0): Permission denied : Line in use

    I tried with accounts that were in the group UUCP and not in the group. Yesterday, it made no difference, neither worked. Today, it makes no difference both work. My only guess is that the serial hardware itself got in some kind of confused state.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •