Bash script to change a string in /etc folder?

Question

I am wanting to create a script to change one of the values for the authorization file.   (See Article TS3287 in the KB)
I assumed that I could use the sed command to do this, but I am getting an error when attempting to run.  Any ideas?
Below is the code I wrote ...
#!/bin/bash
OLD="<string>The owner or any administrator can unlock the screensaver.</string>"
NEW="<string>(Use SecurityAgent.) The owner or any administrator can unlock the screensaver.</string>"
DPATH="/etc/authorization"
BPATH="/etc"
TFILE="/tmp/out.tmp.$$"
[ ! -d $BPATH ] && mkdir -p $BPATH || :
for f in $DPATH
do
  if [ -f $f -a -r $f ]; then
    /bin/cp -f $f $BPATH
   sed "s/$OLD/$NEW/g" "$f" > $TFILE && mv $TFILE "$f"
  else
   echo "Error: Cannot read $f"
  fi
done
/bin/rm $TFILE

Answer 1

You do the testing- this script should work->
#!/bin/bash
#This script needs to run as root
ROOT_UID=0
if [[ $UID -ne $ROOT_UID ]]; then
echo "YOU MUST BE ROOT TO RUN THIS SCRIPT"
exit 1
fi
OLD="<string>The owner or any administrator can unlock the screensaver.<\/string>"
NEW="<string>(Use SecurityAgent.) The owner or any administrator can unlock the screensaver.<\/string>"
cp /private/etc/authorization /tmp/auth.tmp
sed "s/$OLD/$NEW/" /tmp/auth.tmp > /tmp/authorization
mv /private/etc/authorization /private/etc/authorization.previous
mv /tmp/authorization /private/etc/authorization
rm /tmp/auth.tmp