Re: cannot open /dev/cua2

[Craig Sanders <cas@taz.net.au>]

On Tue, 25 Nov 1997, Adalberto da Silva wrote:

> I'm trying to set my modem under Linux. I've made a few tests as root
> with minicom and it's working fine for AT commands and for dialing and
> transferring files with zmodem protocol.
>
> But it reffuses to work with common users and gives me this message
> when a try to run minicom:
> 
> 	> minicom: cannot open /dev/cua2: Permission denied
> 
> 	With ls -l cua* I get:
> 
> > crw-rw----   1 root     dialout    5,  64 Jan 18  1997 cua0
> > crw-rw----   1 root     dialout    5,  65 Jan 18  1997 cua1
> > crwxrw----   1 root     dialout    5,  66 Nov 25 00:57 cua2
> > crw-rw----   1 root     dialout    5,  67 Jan 18  1997 cua3
> 
> 	How can I enable an user to access /dev/cua2? Is it just enable
> write-read-execution for all users? Is this a secure option (ok, I'm on
> a stand-alone linux box but ...)?

1.  put users who need to run minicom into the "dialout" group.  edit
    /etc/groups and add usernames to the "dialout::20:" line.

    use the 'vigr' command to edit /etc/groups.  it locks the file so that
    it can't be written to by anything else.  probably irrelevant on a
    one-sysadmin machine, but it's a good habit to get into.  you should
    run 'vipw' whenever you edit the /etc/passwd file for the same reason. 

    remember to set your EDITOR env variable before you run vigr otherwise
    you'll get the ae editor.  (i consider this to be a bug - it violates 
    the principle of least surprise - but other debian developers
    disagree).  e.g.

		export EDITOR=/usr/bin/vi
	or
		export EDITOR=/usr/bin/joe

    or whatever your favourite editor is.


2.  don't use /dev/cua* devices.  ever.  they are obsolete and have been
    obsolete for well over a year...they only exist for compatibility with
    ancient software which hasn't been modified to use the ttyS devices.
 
    use /dev/ttyS* instead.

    this is important.  you'll run into extremely annoying and frustrating
    device locking problems if you use the cua devices.


craig


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