Question

How to convert a string to lower case or upper case in Bash?

Hi all,

I am writing a script that would take some user input but I want to make sure that the string provided by the user is consistent.

Is there a way to transform a string in bash to all lower case or all upper case?

Thanks!


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Bobby Iliev
Site Moderator
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April 23, 2021
Accepted Answer

Hi there,

There are multiple ways of doing it, but what I personally use is the following syntax:

  • Transform all letters to lower case:
echo "${user_input_variable,,}"
  • Transform only the first letters to lower case:
echo "${user_input_variable,}"
  • Transform all letters to upper case:
echo "${user_input_variable^^}"
  • Transform only the first letter to upper case:
echo "${user_input_variable^}"

Here is a quick demo:

Hope that this helps! Regards, Bobby