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

问题

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 I want it to do: "hELLO wORLD abc"

Please help! =)

回答1:

This will do what you are looking for:

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

回答2:

I think tr '[a-zA-Z]' '[A-Za-z]' is more straight forward, and easier to remember.

回答3:

You can use \L& and \U& to convert to lower and upper case respectively:

$echo "SUJIT dhamale " | sed 's/.*/\L&/g'

Result: sujit dhamale

$ echo "SUJIT dhamale " | sed 's/.*/\U&/g'

Result: SUJIT DHAMALE

来源：https://stackoverflow.com/questions/23178769/unix-tr-command-to-convert-lower-case-to-upper-and-upper-to-lower-case