在Bash中转换字母大小写/判断变量是否为整数

Posted 2021-05-02 普通学习者

(1) 将大写字母转换成小写字母
Var="HELLO WORLD"
# 方法1
echo $Var | tr '[:upper:]' '[:lower:]'
# 方法2
echo $Var | tr '[A-Z]' '[a-z]'
# 方法3
echo $Var | awk '{print tolower($0)}'
# 方法4
echo $Var | perl -ne 'print lc'

(2) 判断一个变量是否是整数
Var=123
# 方法1
if [[ $Var =~ ^[0-9]+$ ]]
then
   echo $Var is an integer
else
   echo $Var is not an integer
fi

# 方法2
case $Var in
    ''|*[!0-9]) echo $Var is not an integer;;
    *) echo $Var is an integer;;
esac

参考：
(1) https://stackoverflow.com/questions/2264428/converting-string-to-lower-case-in-bash
(2) https://stackoverflow.com/questions/806906/how-do-i-test-if-a-variable-is-a-number-in-bash