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
Thanks in advance.
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LEARN ABOUT OPENSOLARIS
shells
shells(4) File Formats shells(4)
NAME
shells - shell database
SYNOPSIS
/etc/shells
DESCRIPTION
The shells file contains a list of the shells on the system. Applications use this file to determine whether a shell is valid. See getuser-
shell(3C). For each shell a single line should be present, consisting of the shell's path, relative to root.
A hash mark (#) indicates the beginning of a comment; subsequent characters up to the end of the line are not interpreted by the routines
which search the file. Blank lines are also ignored.
The following default shells are used by utilities: /bin/bash, /bin/csh, /bin/jsh, /bin/ksh, /bin/ksh93, /bin/pfcsh, /bin/pfksh, /bin/pfsh,
/bin/sh, /bin/tcsh, /bin/zsh, /sbin/jsh, /sbin/sh, /usr/bin/bash, /usr/bin/csh, /usr/bin/jsh, /usr/bin/ksh, /usr/bin/ksh93, /usr/bin/pfcsh,
/usr/bin/pfksh, /usr/bin/pfsh, and /usr/bin/sh, /usr/bin/tcsh, /usr/bin/zsh, and /usr/sfw/bin/zsh. /etc/shells overrides the default list.
Invalid shells in /etc/shells could cause unexpected behavior, such as being unable to log in by way of ftp(1).
FILES
/etc/shells list of shells on system
SEE ALSO
vipw(1B), ftpd(1M), sendmail(1M), getusershell(3C), aliases(4)
SunOS 5.11 20 Nov 2007 shells(4)