Bash 脚本 - 如果有条件 [ ]

Question

我有下面的代码并收到以下错误输出:

Enter your exam score
40
./if2.sh: line 6: 40: No such file or directory
Very well done. You have an A grade.

我在 CentOS 上使用 bash 4.1.2(1)。

#!/bin/bash
#This script demonstrates the if-then-elif format.

echo "Enter your exam score"
read exam_pct
if [ $exam_pct < 40 ]
then
    echo "Sorry, you have failed."
elif [ $exam_pct > 70 ]
then 
    echo "Very well done. You have an A grade."
else
    echo "Well done. You passed."
fi

这里有什么问题吗？

Answer 1

if [ $exam_pct < 40 ]应该是 if [ "$exam_pct" -lt 40 ]

if [ $exam_pct > 70 ]应该是 if [ "$exam_pct" -gt 70 ]

请始终引用您的变量。

查看此以获取更多详细信息 - http://tldp.org/LDP/abs/html/comparison-ops.html