Shell Programming and Scripting

I trying to replace a value with some other value in a file using sed command. Both the replacing and replacable values may contain special charcters (example old value="c:\\tmp" and new value="/tmp")

Below is the code i am using.
sed s/FCR.BASEIN_BACKUP=c:\\temp/FCR.BASEIN_BACKUP=/tmp/g /opt/test.properties > /opt/test.properties

the following is the error i am facing.
sed: command garbled: s/FCR.BASEIN_BACKUP=c:\\temp/FCR.BASEIN_BACKUP=/tmp/g /opt/test.properties

The file in which i am trying to replace (/opt/test.properties) is getting emptied (filesize 0) when i run the above command

Your help is greatly appreciated.

Your problem is actually rather simple:
Because you mention '/' right after the 's' command, sed assumes '/' is your delimiter.
Take a look at your like and see if you can spot the number of '/'s.
The simplest way around this is by using another (unused) character as delimiter.
Ex:
sed s#FCR.BASEIN_BACKUP=c:\\temp#FCR.BASEIN_BACKUP=/tmp#g /opt/test.properties > /opt/test.properties