printing via serial to usb cable

[Wade Smart]

Rashkae wrote:
> Wade Smart wrote:
>> Rashkae wrote:
>>> Wade Smart wrote:
>>>> 20090128 0906 GMT-5
>>>>
>>>> I recently posted about my parallel to usb cable causing lots of 
>>>> problems on my system - and since I received no help there I decided to 
>>>> try something else.
>>>>
>>>> I borrowed a serial to usb cable. I was able to print a test page by:
>>>> sudo echo "Printer Test" > /dev/ttyUSB0
>>>>
>>>> but I havent been able to print any other way.
>>>>
>>>> In cups I changed the uri to usb://dev/ttyUSB0 and then I ran the 
>>>> configure script but nothing changed.
>>>>
>>>> What else can I try?
>>>>
>>>> Wade
>>>>
>>> Try a serial URI
>>>
>>> ex: serial:/dev/ttyUSB0?baud=11500
>>>
>>> Also note: I think (without being absolutely certain) that you only use
>>> 1 / when you refer to a file (or a device note) directly on your system,
>>> use // when your are specifying a network resource.  I don't know if
>>> that matters or if CUPS is smart enough to figure that out on it's own.
>>>  ( // also seems to be used by USB printers that are named by their
>>> model number rather than a device note, for examply, in my system, I
>>> have usb://Samsung/ML-1740  compared to parallel:/dev/lp0)
>>>
>> 20090128 1007 GMT-5
>>
>> Okay... LaserJet4050 (Default Printer) "Unable to open device file 
>> "/dev/ttyUSB0": Permission denied"
>>
>> And in my logs:
>> Jan 28 10:05:42 wadesmart kernel: [145933.655140] 
>> audit(1233158742.764:27): type=1503 operation="inode_permission" 
>> requested_mask="rw::" denied_mask="rw::" name="/dev/ttyUSB0" pid=28751 
>> profile="/usr/sbin/cupsd" namespace="default"
>>
>> Jan 28 10:05:43 wadesmart kernel: [145934.058182] 
>> audit(1233158743.168:28): type=1503 operation="inode_permission" 
>> requested_mask="::rw" denied_mask="::rw" name="/dev/tty" pid=28757 
>> profile="/usr/sbin/cupsd" namespace="default"
>>
>> Jan 28 10:06:26 wadesmart kernel: [145977.419281] 
>> audit(1233158786.616:29): type=1503 operation="inode_permission" 
>> requested_mask="rw::" denied_mask="rw::" name="/dev/ttyUSB0" pid=28801 
>> profile="/usr/sbin/cupsd" namespace="default"
>>
>> Jan 28 10:06:27 wadesmart kernel: [145977.820661] 
>> audit(1233158787.020:30): type=1503 operation="inode_permission" 
>> requested_mask="::rw" denied_mask="::rw" name="/dev/tty" pid=28808 
>> profile="/usr/sbin/cupsd" namespace="default"
>>
>> Wade
> 
> By default, Ubuntu gives read/write permission to User root and group lp
> for printer devices.
> 
> Unfortunately, the device scripts probably don't realize your serial
> device is supposed to be a printer device, and therefore lp group (which
> cups user is probably using) doesn't have write permission.
> 
> You can test with the following:
> 
> first, make sure that the device is not a symlink to somewhere else.
> 
> ls -lh /dev/ttyUSB0
> 
> then, assuming we have the correct device file:
> 
> sudo chown root:lp /dev/ttyUSB0
> 
> sudo chmod 660 /dev/ttyUSB0
> 
> 
> Then try printing again and let us know if it works.  Unfortunately,
> making these changes permanent requires a bit more voodoo.. Hopefully
> someone can step in, else I'll research it further.
> 
> PS: Karl has a well known habit on this list to jump in to topics way
> over his head to either hilarious or catastrophic result.  I suggest
> liberal use of salt grains.
> 

20090128 1200 GMT-5

I did the above and I have the following:

logs:
Xorg.0.log: (WW) Open ACPI failed (/var/run/acpid.socket) (Connection 
refused)

Message:
Jan 28 11:59:37 wadesmart kernel: [152755.014555] 
audit(1233165577.832:39): type=1503 operation="inode_permission" 
requested_mask="rw::" denied_mask="rw::" name="/dev/ttyUSB0" pid=1745 
profile="/usr/sbin/cupsd" namespace="default"

Jan 28 11:59:37 wadesmart kernel: [152755.144901] 
audit(1233165577.964:40): type=1503 operation="inode_permission" 
requested_mask="::rw" denied_mask="::rw" name="/dev/tty" pid=1752 
profile="/usr/sbin/cupsd" namespace="default"

restarted cups and this is on the Printers page after refreshing:
LaserJet4050 (Default Printer) "Unable to open device file 
"/dev/ttyUSB0": Permission denied"

Wade

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