Arch Linux

tuxAssistant

Member

Registered: 2013-06-03

Posts: 2

uucp for serial access work any more ?

being member of the uucp group, used to be enough to use the serial ports:

# ls -l /dev/ttyS*
crw-rw---- 1 root uucp 4, 64 Jun  3 07:47 /dev/ttyS0
crw-rw---- 1 root uucp 4, 65 Jun  3 07:47 /dev/ttyS1
crw-rw---- 1 root uucp 4, 66 Jun  3 07:47 /dev/ttyS2
crw-rw---- 1 root uucp 4, 67 Jun  3 07:47 /dev/ttyS3

despite the above when ever using minicom I get "Cannot create lockfile!"

after seaching around, I've tried to crete the file /etc/udev/rules.d/99-local.rules:

KERNEL=="ttyS*", GROUP="uucp", MODE="0666"
KERNEL=="ttyUSB*", GROUP="uucp", MODE="0666"

but there is still no access for normal users, any hint appreciated

mich41

Member

Registered: 2012-06-22

Posts: 796

Re: uucp for serial access work any more ?

being member of the uucp group, used to be enough to use the serial ports:

# ls -l /dev/ttyS*
crw-rw---- 1 root uucp 4, 64 Jun  3 07:47 /dev/ttyS0
...

And apparently still is.

despite the above when ever using minicom I get "Cannot create lockfile!"

By default, minicom creates "lock files" to prevent concurrent sessions on the same port. It seems that you killed minicom and it left a stale lock file. They are somewhere in /var, I'm sure man explains how to get rid of them.

tuxAssistant

Member

Registered: 2013-06-03

Posts: 2

Re: uucp for serial access work any more ?

thanks, but lockfiles are created in /run as LCK..ttS*, there is no lock file

running minicom as root it works, I can se the lockfile gets created and deleted again when minicom closes - does normal user need access to /run, doesn't seem like a good solution  ?

mich41

Member

Registered: 2012-06-22

Posts: 796

Re: uucp for serial access work any more ?

That's weird. When I run minicom as root, it does indeed create a lockfile in /run. But when I run it from my user account, it simply doesn't. And I tried to remove my custom config files.

Anyway, there's the -o option which skips locking and attempts at modem initialization. If you use minicom to connect to some embedded system over null-modem cable it's a no-brainer. For such purposes I start minicom with

minicom -oD /dev/ttyWhatever

If you use only one port, it's probably possible to specify both the port and no-init mode in config files.

Last edited by mich41 (2013-06-03 12:02:27)