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Old 09-12-2012, 04:15 PM   #1
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cu does not permit connection to a modem


I have a desktop running Fedora 17 with uucp installed. However, I cannot run the cu command to connect to a dial up modem which is connected to my serial port. It keeps saying line in use. I changed the rwx permissions on /dev/ttyS0 with no luck. Can anyone please help?

Old 09-13-2012, 08:58 AM   #2
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If you run "lsof /dev/ttyS0" what does it show?

You may need to disable the process that conditions the port (e.g. a getty line of some sort in /etc/inittab). Haven't done modems on Linux but on other *nix there is usually something running a getty of some sort to set parameters on the modem and the line in inittab will have "respawn" in it. Respawn tells it to restart the process every time it dies so you might need to change that line to "off" then run "init q" to make it reread and turn off the getty.
Old 09-13-2012, 09:13 AM   #3
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I ran ps ax | grep 'getty' and it shows nothing. I don't have a getty running but the port (ttyS0) seems to be locked. Don't know how to unlock it..
Old 09-13-2012, 10:05 AM   #4
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I had to add the user to the dialout group and it is now working. I am able to run the cu command and connect to a dial up modem
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