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Full Discussion: Grabbing variables and comparing
Top Forums Shell Programming and Scripting Grabbing variables and comparing Post 302225810 by kerpm on Sunday 17th of August 2008 04:27:00 AM
Old 08-17-2008
Grabbing variables and comparing
I have two computers with dynamic IP addresses and am using dyndns so that they are identifiable as the same computer even if their IPs change (we'll call them host1.dyndns.com and host2.dyndns.com). I also have a remote server which I would like to store my computers' IP addresses on. There is a file on my remote server which has the IPs that the two hostnames point to. So the file would look like this

111.111.111.111 #host1.dyndns.com
222.222.222.222 #host2.dyndns.com

I need a script that will run this command which gets the IPs of my computers:

/usr/bin/dig +short host1.dyndns.com | /usr/bin/tail -n 1
/usr/bin/dig +short host2.dyndns.com | /usr/bin/tail -n 1

Then compare the result (which is an IP address) to the file that I have described above. If the IP is different from the old one then remove that line and replace it with the new IP. I thought I could do this myself but grabbing the old IP and storing it in a variable and then comparing it to the new IP was beyond me. I don't even know if that is how you should do it. sed/awk is preferable but any language will do Smilie

Thanks in advance.
 

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LEARN ABOUT DEBIAN

ez-ipupdate

EZ-IPUPDATE(8)							Dynamic DNS client						    EZ-IPUPDATE(8)

NAME

       ez-ipupdate - dynamic DNS client

SYNOPSIS

       ez-ipupdate [options]

DESCRIPTION

       This manual page documents briefly the ez-ipupdate dynamic DNS client.

OPTIONS

       ez-ipupdate follows the usual GNU command line syntax, with long options starting with two dashes (`-').

       -a, --address <ip address>
	      string to send as your ip address

       -b, --cache-file <file>
	      file to use for caching the ipaddress

       -c, --config-file <file>
	      configuration  file,  almost  all  arguments can be given with: <name>[=<value>] to see a list of possible config commands try "echo
	      help | ez-ipupdate -c -"

       -d, --daemon
	      run as a daemon periodicly updating if necessary

       -e, --execute <command>
	      shell command to execute after a successful update

       -f, --foreground
	      when running as a daemon run in the foreground

       -F, --pidfile <file>
	      use <file> as a pid file

       -g, --request-uri <uri>
	      URI to send updates to

       -h, --host <host>
	      string to send as host parameter

       -i, --interface <iface>
	      which interface to use

       -L, --cloak_title <host>
	      some stupid thing for DHS only

       -m, --mx <mail exchange>
	      string to send as your mail exchange

       -M, --max-interval <# of sec> max time in between updates

       -N, --notify-email <email>
	      address to send mail to if bad things happen

       -o, --offline
	      set to off line mode

       -p, --resolv-period <sec>
	      period to check IP if it can't be resolved

       -P, --period <# of sec>
	      period to check IP in daemon mode (default: 1800 seconds)

       -q, --quiet
	      be quiet

       -r, --retrys <num>
	      number of trys (default: 1)

       -R, --run-as-user <user>
	      change to <user> for running, be ware that this can cause problems with handeling SIGHUP properly if that user can't read the config
	      file. also it can't write it's pid file to a root directory

       -Q, --run-as-euser <user>
	      change  to effective <user> for running, this is NOT secure but it does solve the problems with run-as-user and config files and pid
	      files.

       -s, --server <server[:port]>
	      the server to connect to

       -S, --service-type <server>
	      the type of service that you are using try one of: null ezip pgpow dhs dyndns dyndns-static dyndns-custom ods tzo  easydns  easydns-
	      partner gnudip justlinux dyns hn zoneedit heipv6tb

       -t, --timeout <sec.millisec>
	      the amount of time to wait on I/O

       -T, --connection-type <num>
	      number sent to TZO as your connection type (default: 1)

       -U, --url <url>
	      string to send as the url parameter

       -u, --user <user[:passwd]>
	      user ID and password, if either is left blank they will be prompted for

       -w, --wildcard
	      set your domain to have a wildcard alias

       -z, --partner <partner>
	      specify easyDNS partner (for easydns-partner services)

       --help display this help and exit

       --version
	      output version information and exit

       --credits
	      print the credits and exit

       --signalhelp
	      print help about signals

AUTHOR

       This manual page was written by Sam Hocevar <sam@zoy.org> for the Debian GNU/Linux system (but may be used by others).

ez-ipupdate - 3.0.11b7						   February 2003						    EZ-IPUPDATE(8)
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