主要是用z"$a" == z來判斷是否為Null或是空值
bash-3.2# vi test.sh
#!/bin/bash
if [ z"$a" == z ]; then
echo "a is null"
fi
bash-3.2# ./test.sh
a is null
bash-3.2# vi test.sh
#!/bin/bash
a=""
if [ z"$a" == z ]; then
echo "a is null"
bash-3.2# ./test.sh
a is null
fi
- Jan 30 Fri 2015 11:01
-
Shell Script : If a Variable Is Null Or Not
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