shell大小写字母转换

小写字母转大写字母

[root@Charramma ~]# content="abc"
[root@Charramma ~]# echo $content
abc
[root@Charramma ~]# echo ${content^}
Abc
[root@Charramma ~]# echo ${content^^}
ABC

大写字母转小写字母

[root@TEST-1 Charramma]# content="ABC"
[root@TEST-1 Charramma]# echo $content
ABC
[root@TEST-1 Charramma]# echo ${content,}
aBC
[root@TEST-1 Charramma]# echo ${content,,}
abc