不显示字符：
print -n "Enter password - "
stty -echo
read PASSWORD
stty echo
echo ""
print $PASSWORD
显示*号
function savetty
{
SAVETTY=$(stty -g
}
function hidestty
{
stty raw -echo
}
function resetstty
{
stty ${SAVETTY:-cooked}
stty echo
}
function getpass
{
typeset ans passwd cr=$(print -n "\r") bs=$(print -n "\b")
typeset vname=${1:-PASSWORD}
savetty
hidestty
ans=
passwd=
while :
do
ans=`dd if=/dev/tty count=1 bs=1 2>/dev/null`
case $ans in
$bs)
((${#passwd})) && {
print -n "\b \b"
passwd=${passwd%?}
}
;;
$cr)
break
;;
[[:print:]])
print -n '*'
passwd="${passwd}${ans}"
esac
done
eval $vname='$passwd'
}
getpass PASSWD
resetstty
echo ""
echo "$PASSWD"
read PASSWD
echo "$PASSWD"
