UNIX/Linux shell and returning values from functions

Here is an interesting fact.

Let's assume you want to write a function myfun_initialize()

If the function is supposed to initialize some variables then DO NOT RETURN result of this function through the `function caller` (well, I have just made up this name.)

In other words...

right:

myfun_initialize parameters
[ "$var_initialize" = "ok" ] {
    echo "Oops!"
    return
}

wrong:

[ "`myfun_initialize parameters`" = "ok" ] {
    echo "Oops!"
    return
}

Why is it wrong? I wish I had a simple explanation, but if the myfun_initialize function initializes some external variables you would like to use later on, then by calling `myfun_initialize` you will initialize temporary variables, and these outside of the call will be unchanged!

Test it yourself:


Here is the text

MYVAR="nothing"
 
# $1 - value
myfun() {
    MYVAR="$1"
}
 
echo "MYVAR before calling myfun is $MYVAR"
if [ "`myfun something`" = "" ]
 then
    echo "myfun returned an empty string"
    echo "MYVAR after calling \`myfun something \` is $MYVAR"
 else
    echo "myfun hasn't returned an empty string?!"
    echo "MYVAR after calling \`myfun something\` is $MYVAR"
 fi
 
myfun something
echo "MYVAR after calling myfun something is $MYVAR"
 

So what is the solution?
Use a variable to return the result.
Example:

myfunc() {
    ....
    var_myfunc="ok"
}
 
myfunc
[ "$myfunc" = "ok" ] && {
    ...
}