# Shell 關係運算子範例

```#!/bin/sh

a=10
b=20

if [ \$a -eq \$b ]
then
echo "\$a -eq \$b : a is equal to b"
else
echo "\$a -eq \$b: a is not equal to b"
fi

if [ \$a -ne \$b ]
then
echo "\$a -ne \$b: a is not equal to b"
else
echo "\$a -ne \$b : a is equal to b"
fi

if [ \$a -gt \$b ]
then
echo "\$a -gt \$b: a is greater than b"
else
echo "\$a -gt \$b: a is not greater than b"
fi

if [ \$a -lt \$b ]
then
echo "\$a -lt \$b: a is less than b"
else
echo "\$a -lt \$b: a is not less than b"
fi

if [ \$a -ge \$b ]
then
echo "\$a -ge \$b: a is greater or  equal to b"
else
echo "\$a -ge \$b: a is not greater or equal to b"
fi

if [ \$a -le \$b ]
then
echo "\$a -le \$b: a is less or  equal to b"
else
echo "\$a -le \$b: a is not less or equal to b"
fi```

```10 -eq 20: a is not equal to b
10 -ne 20: a is not equal to b
10 -gt 20: a is not greater than b
10 -lt 20: a is less than b
10 -ge 20: a is not greater or equal to b
10 -le 20: a is less or  equal to b```

• 運算子和表示式之間必須有空格，例如2+2是不正確的，它應該寫成2 + 2。

• if...then...else...fi 語句是下一章節中要解釋的決策宣告。