Why is this Bash script not changing the string's value? - bash

Question

I can't understand why userType is not changing.
I know for certain it's successfully reaching determineType, but it isn't changing the value to "bbb" when I try to print out userType later.
userType="aaa"
function determineType {
userType="bbb"
}
function checkUser {
cat users.csv | \
while read userLine; do
if [[ $userLine =~ .*$user.* ]]
then
determineType
echo "1"
fi
done
echo "0"
}

Answer 1

As soulseekah said in a comment, your while loop is executed in a subshell. Instead, do (and, as a benefit, you get rid of the useless use of cat):
userType="aaa"
determineType() {
userType="bbb"
}
checkUser() {
while read userLine; do
if [[ $userLine = *$user* ]]; then
determineType
return 1
fi
done < users.csv
return 0
}
Note. I also changed a few things:
got rid of the useless regexp since the same can be achieved with globbing,
used more common ways of defining functions in bash,
used return instead of echo for returning values: you'd run into the same problem again with an echo: you'd probably use your function checkUser in another subshell to obtain the value returned by the echo.

Answer 2

You are using a pipe, which launch the while .. do in a subshell.
Changing the value of a variable in a subshell won't affect the original variable
You should replace the:
function checkUser {
cat users.csv | \
while read userLine; do
if [[ $userLine =~ .*$user.* ]]
then
determineType
echo "1"
fi
done
echo "0"
}
with
function checkUser {
while read userLine; do
if [[ $userLine =~ .*$user.* ]]
then
determineType
echo "1"
fi
done < users.csv
echo "0"
}
(This also get rid of a Useless Use Of Cat)