John Marvin wrote:
Larry Alkoff wrote:
As stated in the original post, when I entter the IP with an editor
directly into sip.conf calls work just fine but I am looking for a way
to have that done _automatically_.
The Asterisk - Future of Telephony book says it is possible for
Asterisk to access a Linux environment variable containing the IP
information in the form of "${ENV{variable}}.
It doesn't seem to work. I am asking how to make it work.
Actually, I don't think you read his response carefully enough. He was
giving you a method of doing it automatically.
But first, lets dismiss the environment variable solution. I haven't
played with using environment variables in Asterisk, so I can't help you
there. But I do know about environment variables in general, and you
cannot use them to solve your problem. Environment variables are not
"global", i.e. if you change one it does not effect the value in all
currently running programs. The "environment" (all of the environment
variables and their values) is inherited from the parent process (it is
passed in by the kernel on the new processes stack when the process
first starts). After that, only the process itself can change its own
values in order to pass on a changed value to a child (but again, only
when that child process is started, i.e. a parent cannot affect the
environment of an already running child process). In summary, you can't
change the values of Asterisk's environment variables after Asterisk has
already started. The values that Asterisk sees are the values that it
inherited from its parent process, i.e. most likely the rc scripts that
started Asterisk when you first booted the machine.
Now, back to the solution proposed by Brad. He was in effect proposing
that you dynamically change sip.conf. However, parsing a rewriting
sip.conf automatically is kind of ugly, but luckily Asterisk supports
#include. So, he suggested that you can periodically generate a file
with a single line in it, i.e. "externip=xx.xx.xx.xx" and then use
#include in your sip.conf to include it (i.e. sip.conf doesn't have to
ever change). The final part of the solution is to make Asterisk reread
sip.conf (and the included dynamically created file at the same time).
You can do that with:
asterisk -rx "sip reload"
which you can put into the same cron job that you currently are using to
refresh /etc/myip.
John
John you are quite correct about Brad's solution and I have to thank you
both. I thought again about Brad's post last night in bed - where I do
my best work <g>.
The #include route is indeed a way to go.
In the meantime, I've found more about externhost which was implemented
in Asterisk 1.20+.
I put a line in sip.conf of
externhost=myhost.dyndns.org
with a refresh of 6 hours against the default of 10 seconds ala
externrefresh=21600
This seems to be working nicely but, if there are problems, I'll change
to #include.
You are also correct that environmental variables will not refresh until
the Asterisk shell is reloaded - hopefully not often!
It would still be nice to be able to access shell variables from within
the CLI and particularly frustrating since the "Asterisk - Future of
Telephony" mentions a specific method on page 92. Perhaps they got the
syntax wrong. I certainly would like a better connection between the
shell and CLI.
Thanks for your explanation and I apologize for not realizing that
Brad's suggestion was spot on.
Larry
--
Larry Alkoff N2LA - Austin TX
Using Thunderbird on Linux
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