minicom questions, need expert
Gene Heskett
gene.heskett at verizon.net
Thu May 15 03:00:30 UTC 2008
On Monday 12 May 2008, Kevin J. Cummings wrote:
>Gene Heskett wrote:
>--
>Kevin J. Cummings
>kjchome at rcn.com
>cummings at kjchome.homeip.net
>cummings at kjc386.framingham.ma.us
>Registered Linux User #1232 (http://counter.li.org)
>
>> On Monday 12 May 2008, Mikkel L. Ellertson wrote:
>>> Gene Heskett wrote:
>>>> But, this command line, which outputs to the screen very nicely if the
>>>> pipe and the rest of the line are removed, seems to send the data to
>>>> /dev/null:
>>>>
>>>> #>cat /dev/ttyUSB1 | lpr -Plp1
>>>
>>> Try something like:
>>> cat /dev/ttyUSB1 | lpr -Plp1 -
>>> or
>>> cat /dev/ttyUSB1 | lpr -Plp1 -- -
>>
>> Either of those give this:
>> [root at coyote ~]# cat /dev/ttyUSB1 | lpr -Plp1 -
>> lpr: Error - unknown option '
>> ^C
>> [root at coyote ~]# cat /dev/ttyUSB1 | lpr -Plp1 -- -
>> lpr: Error - unknown option '-'!
>>
>> Thanks.
>>
>>> From the lp man page:
>>> lp submits files for printing or alters a pending job. Use a
>>> filename of "-" to force printing from the standard input.
>
> From the lpr man page:
>> lpr submits files for printing. Files named on the command line are
>> sent to the named printer (or the system default destination if no
>> destination is specified). If no files are listed on the command-line, lpr
>> reads the print file from the standard input.
>
>So:
>
>cat /dev/ttyUSB1 | lpr -Plp1
>
>should be all that's needed....
sorry about the late rely here Kevin. The above example, except to -Plp3, has
been running for about 4 hours, and I have sent 11 copies of that directory
listing up the /dev/ttyUSB1 cable now with nothing going to that printer, or
when changed to lp1 which is right beside me. Neither that, nor a
cat /dev/ttyUSB1 | lp -d lp3 -
works, both apparently doing exactly the same thing with the data, stuffing it
into a file in /tmp, which is not printed, and which is deleted if I ctl-c
the command line.
That has resulted in some activity I can see with htop, for both cat and lpr,
and there is now a file of some 105k in /tmp that contains these directory
listings. The tail end of this /tmp/file looks like this in text format:
[root at coyote tmp]# tail 482b58beea317
0 2008/05/13 21:00 --e-rewr 6B08 1B01 ed
0 2006/04/21 13:38 --e-rewr 1EF6C 16C wcreate
0 2006/04/21 13:38 --e-rewr 1EF70 439 xmode
0 2008/05/12 13:05 ------wr BFF4 211 GSort
0 2008/05/13 21:54 --e-rewr 3FF0 4EA noautoex
0 2008/05/13 21:09 --e-rewr FEDC 4EA multivue
0 1995/04/30 16:30 ----rewr FFF8 39BF GShell
0 1987/09/29 19:27 --e-rewr 1ECAC 3A6E Control
0 1988/02/19 20:02 --e-rewr 1ECB4 1DE compare
And in hexdump -C format:
00003c20 38 20 20 20 20 20 20 33 39 42 46 20 47 53 68 65 |8 39BF GShe|
00003c30 6c 6c 0a 20 20 20 30 20 20 31 39 38 37 2f 30 39 |ll. 0 1987/09|
00003c40 2f 32 39 20 31 39 3a 32 37 20 20 2d 2d 65 2d 72 |/29 19:27 --e-r|
00003c50 65 77 72 20 20 20 31 45 43 41 43 20 20 20 20 20 |ewr 1ECAC |
00003c60 20 33 41 36 45 20 43 6f 6e 74 72 6f 6c 0a 20 20 | 3A6E Control. |
00003c70 20 30 20 20 31 39 38 38 2f 30 32 2f 31 39 20 32 | 0 1988/02/19 2|
00003c80 30 3a 30 32 20 20 2d 2d 65 2d 72 65 77 72 20 20 |0:02 --e-rewr |
00003c90 20 31 45 43 42 34 20 20 20 20 20 20 20 31 44 45 | 1ECB4 1DE|
00003ca0 20 63 6f 6d 70 61 72 65 0a 0a 1b | compare...|
perhaps there is a clue here, like some control character missing?
As the src machine is not sending \n's, only \r's, /dev/ttyUSB1 is set to
translate \r's to \n's with stty options.
Does it need an EOF ($1B) to trigger the actual printing? I'm not sure I can
make the src machine do that, but I'll try. Yes, I could, but as a separate
line of the program and it shows in the above hexdump. As a test its ok, but
for day to day operations it would be a dud.
lpr is the owner of this file according to "lsof|grep lpr":
lpr 3533 root 4u REG 8,3 15531
82903079 /tmp/482b9fa495624
And just now, switching screens, I locked the machine up tight and had to hit
the reset button. 6 day uptime for 2.6.26-rc1 wrecked.
Perhaps the trigger for lpr to actually print it is some other control
character? I'm bumfuzzled to be sure, 2 days of screwing with this.
Many thanks, to Kevin J. Cummings, or anyone else who can shed some light on
this.
>--
>Kevin J. Cummings
>kjchome at rcn.com
>cummings at kjchome.homeip.net
>cummings at kjc386.framingham.ma.us
>Registered Linux User #1232 (http://counter.li.org)
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
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