dk_replace_script.sh v0.2

#!/bin/bash
VERSION="0.2"
#__________________________________________________________
# Authors:      Daren Karupudayyan (& phillips321.co.uk)
# License:      CC BY-SA 3.0
# Use:          paremeter replace
# Released:     www.phillips321.co.uk
#
# dirty script hopefully will replace 2 constant parameters as described below
#  target.xml is the file in which 2 parameters will be replaced
#  from file1.txt and file2.txt
#  the two parameters are constant xxx and yyy
#
# @DK - Do you mean you have a file [target.xml] and you want to find and replace 2 values within it?
#       Value xxx will be replaced with the contents of file1.txt and yyy with file2.txt?
#       If this is the case then the following code with do that
#__________________________________________________________

f_usage(){      #outputs usage information
    echo "MESSAGE: dk_replace_script.sh ${VERSION}"
    echo "MESSAGE: Usage: `basename ${0}` [location/of/target.xml]"
    echo "MESSAGE: # `basename ${0}` /jobs/company/fudgepacker.xml"
    echo "MESSAGE:"
}
f_yesorno(){    #returns 1 if yes is selected
    read -e CONFIRM
    case $CONFIRM in
        y|Y|YES|yes|Yes)
            return 1 ;;
        *)
            return 0 ;;
    esac
}
f_valueset(){   #checks to see if targets.xml is given
    if [ -z ${1} ]
    then
        f_usage
        exit 1
    fi
    TARGETXML="${1}"
    XXX=`cat file1.txt`  # like the use of xxx :-D
    YYY=`cat file2.txt`
    echo "MESSAGE: using file ${TARGETXML}"
    echo "MESSAGE: XXX to be replaced as ${XXX}"
    echo "MESSAGE: YYY to be replaced as ${YYY}"
}
f_replacer(){
    echo "MESSAGE: replacing xxx with ${XXX}"
    echo "MESSAGE: replacing yyy with ${YYY}"
    sed s/xxx/${XXX}/g s/yyy/${YYY}/g ${TARGETXML} >> ${TARGETXML}_output.xml
}
f_confirm(){
    echo -n "MESSAGE: Is the above correct?(yes/no): "
    f_yesorno && exit 0
    f_replacer
}

f_valueset
f_confirm
exit 0