Several ways for MAC to set environment variable path

Mac typically uses bash as the default shell

Environment variables for Mac systems, loaded in the order:
/etc/profile/etc/paths ~/.bash_profile ~/.bash_login ~/.profile ~/.BASHRC
Of course/etc/profile and/etc/paths are system-level, the system boot will be loaded, the following are the current user-level environment variables. The next 3 are read in the previous order, if the ~/.bash_profile file exists, then the next few files will be ignored, if the ~/.bash_profile file does not exist, and so on to read the following file. ~/.BASHRC does not have the above rule, it is loaded when the bash shell is opened.

If no special instructions are specified, the syntax for setting path is:
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12	#中间用冒号隔开     export PATH=$PATH:<PATH 1>:<PATH 2>:<PATH 3>:------:<PATH N>

(i) Global settings
The following file settings are global and require root access when modified

1)/etc/paths (global recommendation to modify this file)
Edit paths, add environment variables to the paths file, one line at a path
Hint: When entering environment variable, do not enter one by one, just drag the folder into Terminal.

2)/etc/profile (recommended not to modify this file)
A global (public) configuration that reads the file when logged on, regardless of the user.

3)/ETC/BASHRC (typically add system-level environment variables to this file)
Global (public) configuration, which will be read by the bash shell, regardless of the way it is executed.

4)
1. Create a file:
sudo touch/etc/paths.d/mysql
2. Open this file with vim (if it is opened in open-t, edit is not allowed):
sudo vim/etc/paths.d/mysql
3. Edit the file, type the path and save (Close the Terminal window and reopen one to use the MySQL command)
/usr/local/mysql/bin
It is said that it is possible to generate new files on their own, without having to put the variables in a paths file for easy management.

(ii) Individual user settings

1) ~/.bash_profile (add user-level environment variable in any file)
(Note: Linux is. BASHRC and Mac is. Bash_profile)
This file will not be read until the bash shell is executed in login mode. The file is only executed once! By default, he sets some environment variables
Set command aliases alias Ll= ' Ls-la '
Set Environment variables:

1	export PATH=/opt/local/bin:/opt/local/sbin:$PATH

2) ~/.BASHRC Ibid.

If you want to take effect immediately, you can execute the following statement:
$ source The corresponding file
After the general environment variable is changed, the restart takes effect.

Several ways for MAC to set environment variable path