Shell, Bash, and terminal configuration files

Shell--command parser, also a programming language
Bash-a specific instance of the shell, zsh, bash are instances of the shell

The "Echo $SHELL" command can be used in the terminal to view the shell instance currently in use and can be switched to zsh or other shell instances through "Chsh-s/bin/zsh" .

Global profile (all in/etc/directory, etc for Environment config abbreviation):

/etc/profile (not recommended)--each user is called at logon

/ETC/BASHRC (it is recommended to set the global environment variable here, only for bash)--each user calls/etc/paths when bash is open (it is recommended to configure the Global environment variable here)--one line at a time, Additional configuration files can be appended with the PATH as follows: "Export path= $PATH: [Path1]:[path2]:[path3]......:[pathn]"

User profiles: (both in the ~/home directory)

~/.bash_profile (recommended here to configure user environment variables, only valid for bash)--called when the current user is logged on

~/.BASHRC (recommended to configure user environment variables here, only valid for bash)--called when the current user bash is open

Note: If you are using zsh or another shell instance, it is likely that it will not invoke the above-mentioned configuration files that are only valid for bash, so you can add "source ~/.bash_profile" to the ~/.ZSHRC (zsh user profile) Similar directives to make them effective.