'How should I redirect stderr on commands that with arguement?

I have a shell script I want to do: ./xxx.sh -a 1 -b 2 -c 3 2>/dev/null

However, the 2 is treated as argument

Similerly with the following command echo test 2>aaa.txt

my intention is to direct strerr to aaa.txt, however, I got:

cat aaa.txt
test 2

as you can see 2 is also treated as an argument. How should I redirect stderr on commands that with argument?

linux shell

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