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为什么要测试$？ -eq 0 为真，即使我期望它为假

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为什么要测试$？ -eq 0 为真，即使我期望它为假

仍在与这个 shell 脚本（密码验证）作斗争，我已经寻找解决方案，但我仍然找不到正确的解决方案。

#!/bin/sh

echo "enter the password"
read password

len="${#password}"

if test $len -ge 8 ; then
    echo "$password" | grep -q [A-Z]
    echo "$password" | grep -q [a-z]
    echo "$password" | grep -q [0-9]

    if test $? -eq 0 ; then
      echo "Strong password"
    else
      echo "Weak password"
    fi

else
    echo "password lenght should be greater than or equal 8"
fi

该脚本的结果如下：

# ./password.sh 
enter the password
12345678
Strong password >> Not as I expected which is should be weak password

我的错在哪里？

答案1

一些东西：

  • 使用readwithout会使密码-r变得困难。\

  • 不引用正则表达式将使 shell 将它们视为通配模式，并且它们将扩展为文件名。

  • 该$?变量将仅保存最后一个的退出状态grep。

考虑以下bash脚本：

#!/bin/bash

read -r -p "password:" -s password

if (( ${#password} < 8 )); then
  echo "Passwords need 8 or more characters"
  exit 1
fi

has_upcase=0
has_locase=0
has_digit=0
has_other=0

case "$password" in
  *[[:upper:]]*) has_upcase=1 ;;&
  *[[:lower:]]*) has_locase=1 ;;&
  *[[:digit:]]*) has_digit=1  ;;&
  *[^[:alnum:]]*) has_other=1 ;;
esac

if (( !has_upcase )); then
  echo "Make sure you password has at least one upper-case letter"
elif (( !has_locase )); then
  echo "Make sure your password has at least one lower-case letter"
elif (( !has_digit )); then
  echo "Make sure your password has at least one digit"
elif (( !has_other )); then
  echo "Make sure your password has at least non-alphanumeric character"
else
  echo "Your password is ok"
fi

我冒昧地在测试中添加了“非字母数字”要求。

of能够向用户提供提示，并在不回显键入内容的情况下进行阅读read。bash

该case语句检查输入的密码是否至少包含 1 个大写字母、1 个小写字母、1 个数字和 1 个非字母数字字符（使用POSIX 字符类）。;;&每行末尾的时髦外观意味着“继续使用该字符串测试下一个模式”。

要获得sh它的 POSIX 变体，请将其替换read为

stty -echo
printf "password: "
read -r password
stty echo
printf "\n"

以及case类似的声明

case "$password" in *[[:upper:]]*) has_upcase=1 ;; esac
case "$password" in *[[:lower:]]*) has_locase=1 ;; esac
case "$password" in *[[:digit:]]*) has_digit=1  ;; esac
case "$password" in *[^[:alnum:]]*) has_other=1 ;; esac

其余的应该还是POSIX。

答案2

您的grep调用将按顺序运行，并且$?仅等于grep脚本中的最后一个调用。你会想在每个之后使用类似的东西grep：

retCodes=0
echo "$password" | grep -q "[A-Z]"
retCodes=$(($retCodes + $?))

echo "$password" | grep -q "[a-z]"
retCodes=$(($retCodes + $?))

echo "$password" | grep -q "[0-9]"
retCodes=$(($retCodes + $?))

这if [[ $retCodes -eq 0 ]]; then ...

答案3

也许这会有所帮助：

#!/bin/sh

echo "enter the password"
read -r password

caps="$(echo "$password" | sed 's/[^A-Z]//g')"
lowers="$(echo "$password" | sed 's/[^a-z]//g')"
numbers="$(echo "$password" | sed 's/[^0-9]//g')"

if [ "${#password}" -lt 8 ]; then
    echo "password lenght should be greater than or equal 8"
else
    echo "caps=${#caps} lowers=${#lowers} numbers=${#numbers}"
    if [ "${#caps}" -ge 1 ] && [ "${#lowers}" -ge 1 ] && [ "${#numbers}" -ge 1 ]; then
        echo "Strong password"
    else
        echo "Weak password"
    fi
fi

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