Mastering Linux Shell Scripting - Second Edition

Returning values from functions

Whenever we have statements that are printed on the screen within the function, we can see their result. However, lots of times we will want the function to populate a variable within the script and not display anything. In this case, we use return in the function. This is especially important when we are gaining input from users. We may prefer the case to translate the input to a known case to make the condition testing easier. Embedding the code in a function allows it to be used many times within a script.

The following code shows how we can achieve this by creating the to_lower function:

to_lower () 
{ 
    input="$1" 
    output=$( echo $input | tr [A-Z] [a-z]) 
return $output 
} 

Stepping through the code, we can ...