At login, Zsh sources the following files in this order:
~/.zshenv This file should contain commands to set the command search path,
plus other important environment variables; it should not
contain commands that produce output or assume the shell is
attached to a tty.
/etc/profile This file is sourced by all Bourne-compatible shells upon login:
it sets up an environment upon login and application-specific
(/etc/profile.d/*.sh) settings.
~/.zprofile This file is generally used for automatic execution of user's scripts.
~/.zshrc This is Zsh's main configuration file.
~/.zlogin This file is generally used for automatic execution of user's scripts.
~/.zlogout Sourced at logout which is used for automatic execution of user's scripts.