I checked .bashrc .bash_profile and /etc/profile but can't find any hint. A funny thing is that if I source /etc/profile in .bashrc, the "stderr is not a tty - where are you?" error will appear. If I "cp /etc/profile ~/profile" and then source ~/profile in .bashrc, there will be no such error message. Even if I delete /etc/profile and still keep ". /etc/profile" in .bashrc, the error message appears. Anyone knows what's wrong? Thanks in advance.
By the way, thanks tty and echo for your previous kind reply.