#How to replace an active file (library, /bin/ksh, ...)

FILE=/usr/lib/libC.a
NEWCOPY=/tmp/libC.a

#get correct perms for "new" file
cp -p $FILE $FILE.new >> $ERR_FILE 2>&1

cp $NEWCOPY $FILE.new >> $ERR_FILE 2>&1
ln -f $FILE $FILE.old >> $ERR_FILE 2>&1
mv $FILE.new $FILE >> $ERR_FILE 2>&1
rm $FILE.old >> $ERR_FILE 2>&1