Linux bash '[: -ge: unary operator expected' 错误

Question

#!/bin/bash


SubValue()
{


  romanvalue="${romanvalue}$2"
  decvalue=$(( $decvalue - $1 ))

}

if [ $decvalue -ge 1000 ] ; then
  SubValue 1000 "M"
elif [ $decvalue -ge 900 ] ; then
  SubValue 900 "CM"
elif [ $decvalue -ge 500 ] ; then
  SubValue 500 "D"
elif [ $decvalue -ge 400 ] ; then
  SubValue 400 "CD"
elif [ $decvalue -ge 100 ] ; then
  SubValue 100 "C"
elif [ $decvalue -ge 90 ] ; then
  SubValue 90 "XC"
elif [ $decvalue -ge 50 ] ; then
  SubValue 50 "L"
elif [ $decvalue -ge 40 ] ; then
  SubValue 40 "XL"
elif [ $decvalue -ge 10 ] ; then
  SubValue 10 "X"
elif [ $decvalue -ge 9 ] ; then
  SubValue 9 "IX"
elif [ $decvalue -ge 5 ] ; then
  SubValue 5 "V"
elif [ $decvalue -ge 4 ] ; then
  SubValue 4 "IV"
elif [ $decvalue -ge 1 ] ; then
  SubValue 1 "I"
fi

我尝试了这段代码，它给出了许多错误

dectoroma.sh: line 13: [: -ge: unary operator expected dectoroma.sh: line 15: [: -ge: unary 
operator expected
dectoroma.sh: line 17: [: -ge: unary operator expected
dectoroma.sh: line 19: [: -ge: unary operator expected
dectoroma.sh: line 21: [: -ge: unary operator expected
dectoroma.sh: line 23: [: -ge: unary operator expected
dectoroma.sh: line 25: [: -ge: unary operator expected
dectoroma.sh: line 27: [: -ge: unary operator expected
dectoroma.sh: line 29: [: -ge: unary operator expected
dectoroma.sh: line 31: [: -ge: unary operator expected
dectoroma.sh: line 33: [: -ge: unary operator expected
dectoroma.sh: line 35: [: -ge: unary operator expected
dectoroma.sh: line 37: [: -ge: unary operator expected

谁能帮我解决这个问题。

Answer 1

问题中报告的问题根源是一个空的decvalue，如 syme已经说明了。

考虑到脚本的目的，您似乎试图编写一个递归函数。因此，我建议您关注 jww 的问题下有关调试的评论!

此外，我们鼓励您在 recursive functions in bash 上搜索问题就这样。 bash 中的阶乘计算有很好的答案。

想想哪些数量被“传输”，哪些数量最终被返回/编译。

<小时/>

如果您确实遇到困难，您可以找到下面 90% 的解决方案。

#!/bin/bash
romanLetters(){
        local decvalue=$1
        local roman
        declare -i decvalue

        if [ $decvalue -ge 1000 ]; then
                romanvalue="M$(romanLetters $((decvalue - 1000)))"
                echo $romanvalue
        elif [ $decvalue -ge 900 ]; then
                romanvalue="CM$(romanLetters $((decvalue - 900)))"
                echo $romanvalue
        # ... and so on ...
        fi
}

echo "1900: $(romanLetters 1900)"