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Full Discussion: Serial Ports - locking them, checking if they are open
Top Forums Programming Serial Ports - locking them, checking if they are open Post 62090 by Oak on Friday 11th of February 2005 09:23:27 AM
Old 02-11-2005
Serial Ports - locking them, checking if they are open
Hi, I'm trying to fix up some serial code that was given to me by a coworker no longer on the project. Problem is, when the program is running and reading the port, I can take away the port by doing a cu command in another terminal window. When I release the cu, the program crashes, I think because it is trying to read a closed port.

I would like to know how to lock the port so the cu will not take it. One of our subcontractors has a program that tells me DEVICE LOCKED if I try the cu trick. I'd like to do that for my port. Does this involve the flock() call?

As a alternative, I'd like to be able to check if the serial port is open before I attempt a read. I'd also like to check if the port is already open before I call my original open. This seems like it would be solved with the stat() call, but I'm not seeing how to make it work.

I appreciate any advice/ideas. FYI, I am working on Solaris 7 and Solaris 8 (have to be compatible with both).

Thanks,
Kate
 

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LEARN ABOUT MOJAVE

nsd-xfer

nsd-xfer(8)                                                         nsd 3.2.12                                                         nsd-xfer(8)

NAME

       nsd-xfer - AXFR client to transfer zones from a name server

SYNOPSIS

       nsd-xfer [-4] [-6] [-a address[@port]] [-p port] [-s serial] [-T tsiginfo] [-v] -z zone -f file servers

DESCRIPTION

       Nsd-xfer is program to transfer zones from a name server using AXFR.  NSD is a complete implementation of an authoritative DNS nameserver.

OPTIONS

       -4     Only send to IPv4 addresses.

       -6     Only send to IPv6 addresses.

       -a address[@port]
              Specify the source address (and port) to send from.

       -f file
              The file to store the zone in.

       -p port
              Specify the port to send to.

       -s serial
              Specify the serial of the current zone. The zone is only transferred if the master server has a zone with a greater serial number.

       -T tsiginfo
              Use  TSIG  to verify the zone transfer. The tsiginfo file must contain the TSIG key information. The file is removed upon successful
              reading of the key. The format of the tsiginfo file is described in the doc/README file (section 3.3).

       -v     Be more verbose.

       -z zone
              Specify the zone to receive.

       servers
              List of nameservers to try.

EXAMPLES

       To run this program the standard way type:

       # nsd-xfer -z foobar.cz -f foobar.cz.zone 1.2.3.4

SEE ALSO

       nsd(8), nsdc(8), nsd.conf(5), nsd-checkconf(8), nsd-notify(8), nsd-patch(8), zonec(8)

AUTHORS

       NSD was written by NLnet Labs and RIPE NCC joint team. Please see CREDITS file in the distribution for further details.

NLnet Labs                                                         jul 19, 2012                                                        nsd-xfer(8)
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