#!/bin/bash

for VHFILE in *
do
    if sed 's/68\.12\.54\.142/65.43.123.23/g' "$VHFILE" > temp.txt \
       && cat temp.txt >> "$VHFILE" \
       && rm -f temp.txt
    then
        echo "Done with \"$VHFILE\"."
    else
        echo "Failure at \"$VHFILE\"."
    fi
done