On Jan 3, 2005, at 11:22 PM, Eric F Crist wrote:
On Jan 3, 2005, at 8:21 PM, Timothy Luoma wrote:
On Jan 3, 2005, at 6:28 PM, Eric F Crist wrote:
A couple more questions, then I'm done. Promise.
I need to verify whether or not there is an entry for grog_firewall_oif and grog_firewall_iif in /etc/rc.conf. If not, I want to exit with an error.
You want to check for either "grog_firewall_oif" or "grog_firewall_iif" in /etc/rc.conf
egrep -v "^#" /etc/rc.conf |\ egrep -q "grog_firewall_oif | grog_firewall_iif" || (echo "$0" ; exit 1)
The first line says "skips the comment lines" (the ones that begin with #)
What does the second line do? I tried, apparently, to accomplish the same thing with some different syntax, yet unsuccessfully.
OOps, sorry. The 2nd line was the more important. I must have gotten distracted while writing the explanation.
egrep -q says "run egrep, but don't tell me anything except an exit code"
egrep is 'extended grep' which can match patterns. See 'man grep' for the difference between grep, egrep, and fgrep, all of which have specific uses. egrep "a|b" means "look for either 'a' or 'b'
egrep -q "grog_firewall_oif | grog_firewall_iif" means "look for either of those grog_firewall_oif or grog_firewall_iif
NOTE: I made a mistake in that there should be NO WHITESPACE around the "|" when doing that match. The corrected version would be
egrep -v "^#" /etc/rc.conf |\ egrep -q "grog_firewall_oif|grog_firewall_iif" || (echo "$0" ; exit 1)
the "||" means "If what happened on the left hand side didn't exit = 0, then do the stuff on the right hand side
ARGH. Another mistake, but at least a minor one. No error message given there. It should look more like:
(echo "$0 did not find grog_firewall settings"; exit 1)
I can assume everything, since grog_firewall_oif *should* be a value such as above. On my system, grog_firewall_oif will be ath0. This isn't assumed, but rather defined for me. I would write the above line as follows (please verify syntax):
ifconfig $grog_firewall_oif |\ tr '\012' ' ' |\ sed 's#.*inet ##; s# netmask.*##'
oif_ip=`ifconfig $grog_firewall_oif |\ tr '\012' ' ' |\ sed 's#.*inet ##; s# netmask.*##'`
yes, that looks good. Do verify that you get the results you expect when you run the commands at the commandline before putting them in a script.
This is a lot of help, however, if you read:
I don't actually need my own address, I need to be able to figure out that the system, based on the above output, is on the 192.168.1.0/24 network.
I need my NETWORK address, in this case 192.168.1.0 (with netmask), which would be 192.168.1.0/24
Ah, ok, so you need the 192.168.1. part and the netmask.
Ok, here's where someone who is better at pattern matching could come up with something elegant, where I end up getting really hacky
(NOTE: i'm using 'en1' here because that's what it is on my system here, adjust for your own setting)
IFCONFIG=`ifconfig en1|tr '\012' ' ' |sed 's#.*inet ##; s#broadcast .*##; s# netmask # #' |tr '.' ' '`
which says, get all the ifconfig information, and trim it down to just the IP and the netmask. Oh, and change any periods for spaces (the reason why will become evident in a moment). At this point, $IFCONFIG on my system would look like this:
192 168 2 102 0xffffff00
then I'd put the netmask in its own variable like this
NETMASK=`echo $IPCONFIG | awk '{print $NF}'`which says "take the $IPCONFIG information and give me the last field. Since we know there will be 5 fields, we could also use this:
NETMASK=`echo $IPCONFIG | awk '{print $5}'`SUBNET=`echo $IPCONFIG | awk '{print $1"."$2"."$3}'`that will make $SUBNET = 192.168.2
(the awk statement says "take the $IPCONFIG information and give me the 1st, 2nd, and 3rd fields and put periods in between them when you print them)
ASIDE: It would be easy to get several different levels of specificity here (i.e. do you want 192.168.2 or just 192.168 or just 192)
Then I would make use of a case statement like this:
case $SUBNET in
192.168.2)
echo "I'm on the office network"
;; 10.0.1)
echo "I'm on my home network"
;;
esacThe same would be true for whatever you want to do with $NETMASK
Does that get at it?
TjL
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