Customizations for interactive shells go into ~/.bashrc. Things that you want to run when you log in go into ~/.profile (or ~/.bash_profile, but it's often not loaded when logging in graphically).

Put this function definition in ~/.bashrc.

Since bash doesn't load .bashrc when it's a login shell, force it to do so: write a ~/.bash_profile containing

. ~/.profile
case $- in *i*) . ~/.bashrc;; esac

i.e. load ~/.profile, and also load ~/.bashrc if the shell is interactive.

See Alternative to .bashrc and the posts linked there.

Customizations for interactive shells go into ~/.bashrc. Things that you want to run when you log in go into ~/.profile (or ~/.bash_profile, but it's often not loaded when logging in graphically).

Put this function definition in ~/.bashrc.

Since bash doesn't load .bashrc when it's a login shell, force it to do so: write a ~/.bash_profile containing

. ~/.profile
case $- in *i*) . ~/.bashrc;; esac

i.e. load ~/.profile, and also load ~/.bashrc if the shell is interactive.

See Alternative to .bashrc and the posts linked there.