egrep "^[0-9]+$" texte.txt
egrep "^[0-9]*(\.[0-9]*)?$" texte.txt
egrep "^([0-9]*)?(\.[0-9]*)?\^[0-9]+$" texte.txt
egrep "^([0-9]*)?(\.[0-9]*)?\^(+|-)?[0-9]+$" texte.txt