How to manage zsh startup files with correct settings.

The shell program uses a collection of startup files that helps users to create an environment. Each file has a specific use and may affect login and interactive environments differently. If an equivalent file exists in your home directory it may override the global settings. This makes it more important to hold the correct information in each file.

So here is the list of startup files along with the details of the information required in them.

.zshenv

This file is always sourced, so it should set environment variables that need to be updated frequently. It often contains exported variables that should be available to other programs, For example, $PATH, $EDITOR are often set in .zshenv. This file is read when zsh is launched to run a single command as well.
The commands which run which runs once and which should be updated on each new shell must be declared in this file.

.zshrc

.zshrc is for interactive shell configuration. We can set the following options for the interactive shell in this file.

• command completion, correction, suggestion, highlighting.
• aliases
• key bindings
• commands history management
• set any variables that are only used in the interactive shell $LS_COLORS.

Non-Interactive shell is used to execute a script for once whereas an Interactive shell is invoked whenever we open a new terminal

.zlogin

.zlogin is sourced at the start of a login shell. This file is sourced after .zshrc file and it helps in maintaining commands to be run when the shell is fully setup.

.zprofile

.zprofile is basically the same as .zlogin except that it's sourced directly before .zshrc is sourced instead of directly after it. According to the zsh documentation, ".zprofile is meant as an alternative to .zlogin. The two are not intended to be used together, although this could certainly be done if desired.".

It is advised to have command in .zprofile which may take some time to complete or variables that are not updated frequently.

.zlogout

It is used to clear and reset the terminal, so it should be used to release all the resources acquired at the time of login.