Unix tr command to convert lower case to upper AND upper to lower case

Question

So I was searching around and using the command `tr` you can convert from lower case to upper case and vice versa. But is there a way to do this both at once? So: ``` $ tr '[:upper:]' '[:lower:]' or $ tr A-Z a-z ``` Will turn "Hello World ABC" to "hello world abc", but what I want is "hELLO wORLD abc".

Accepted Answer

This will do what you are looking for:

```
 tr '[:upper:][:lower:]' '[:lower:][:upper:]'
```

Unix tr command to convert lower case to upper AND upper to lower case

Solution

Problem