My Computer related stuff...

Mac OSX: shell-script to get Network configuration

If you have different "locations" configured in your network environment on mac os x, it could be useful to retrieve what environment is currently selected, to allow different behaviour (in a script for instance) depending on the location/environment.

Mac has an instruction with which you can get this informatio:
networksetup -getcurrentlocation

This command (networksetup) however has to be executed with administrative privileges. This means only a user that's allowed to administer the machine, can execute:
sudo networksetup -getcurrentlocation

A non-administrative user could be interested for this information too. And since this instruction does not change the system configuration, one could think it advisable to set the set-user-ID-on-execution bit of networksetup, using
sudo chmod u+s /usr/sbin/networksetup

However this solution would open up your networsetup for other actions. So this option seems not advisable.
One could write create a script that executes this instruction, and chmod & chown that script to execute as root:
TARGET=GetCurrentLocation.sh;
cat <<EOSCRIPT >GetCurrentLocation.sh
#!/bin/bash
networksetup -getcurrentlocation;
EOSCRIPT
chown root ${TARGET};
sudo chmod 5755 ${TARGET};


Aforementioned snippit will create a script GetCurrentLocation.sh, that does just that.

Another solution is examining /Library/Preferences/SystemConfiguration/preferences.plist
This file holds the required information.

Following script evaluates the contents of that file, and extracts what location is currently selected, without the need for any superuser stuff.

#!/bin/bash
# Filename : GetCurrentNetworkLocation.sh
# Version  : $Revision: 1.1 $
# Author   : Dieter Demerre
# Copyright: (c) 2010- Dieter Demerre
# Licence  : (g) GPL2 (http://www.gnu.org/licenses/)
# Package  : Mac Os X system scripts
# Project  : Network and configuration
# History  :
#  2010-01-12 ddemerre 0.1 Initial implementation
#----------------------------------------------------------------------
# Description
#  script that will (try to) determine what's the current network location
#----------------------------------------------------------------------
INPUT=/Library/Preferences/SystemConfiguration/preferences.plist;

function error
{
  echo ${@} >&2;
}
if [ ! -r "${INPUT}" ]; then
  error "cannot read plist file ${INPUT}"
  exit -1;
fi

#Get key of Currently selected Set 
setInfo=$(grep -A 1 "CurrentSet" "${INPUT}");
if [ 0 -ne ${?} ]; then
  error "could not retrieve CurrentSet info (${?})."
  exit -2;
fi
currentSet=$(echo ${setInfo}|sed 's/[^ ]* *//;s/\/Sets\/\(.*\)<\/string>/\1/;');

#Get line number in file for (start) of definition of the selected set 
notBefore=$(grep -n "<key>${currentSet}</key>" "${INPUT}"|cut -d':' -f 1);
if [ -z ${notBefore} ] || [ ${notBefore} -le 0 ]; then
  error "did not find key reference ${currentSet} in input (result ${notBefore})";
  exit -2;
fi

# Consider only all lines following the definition-start of the set 
lines=$(wc -l "${INPUT}"|awk '{print $1;}');
tail=$(( (lines - notBefore + 1) * 1));
nameInfo=$(tail -n ${tail} "${INPUT}" | grep -A 1 '<key>UserDefinedName</key>');

# And get the string value of the UserDefinedName key.
echo ${nameInfo}|sed 's/[^ ]* *//;s/<string>\([^<]*\)<\/string>.*/\1/;';

Labels: apple, network, script

posted by Dieter @ 16:59