在符合POSIX的外壳中要求输入密码？

当我想在bash脚本中要求输入密码时，可以这样做：

read -s

...但是当我bash以POSIX模式运行时sh，该-s选项被拒绝：

$ read -s
sh: 1: read: Illegal option -s

如何使用POSIX兼容命令安全地请求输入？

read_password() {
  REPLY="$(
    # always read from the tty even when redirected:
    exec < /dev/tty || exit # || exit only needed for bash

    # save current tty settings:
    tty_settings=$(stty -g) || exit

    # schedule restore of the settings on exit of that subshell
    # or on receiving SIGINT or SIGTERM:
    trap 'stty "$tty_settings"' EXIT INT TERM

    # disable terminal local echo
    stty -echo || exit

    # prompt on tty
    printf "Password: " > /dev/tty

    # read password as one line, record exit status
    IFS= read -r password; ret=$?

    # display a newline to visually acknowledge the entered password
    echo > /dev/tty

    # return the password for $REPLY
    printf '%s\n' "$password"
    exit "$ret"
  )"
}

请注意，对于printf未内置的那些shell（mksh），ps如果对所有命令调用及其参数进行了审核，则密码将在输出中清晰显示（几秒钟），或在某些审核日志中显示。

read -s不在POSIX中。如果要兼容POSIX，请使用stty -echo。stty及其echo参数在POSIX中定义。

#!/bin/bash
stty -echo
printf "Password: "
read PASSWORD
stty echo
printf "\n"

这将在所有符合POSIX的shell上工作。

资源