Linux environment variables

The environment variable profile is primarily defined as default environment variables, such as path,histsize, for system default environment variables that are in effect for the operating environment of the system. Path= "$PATH":/root (temporary)
For the environment variable to take effect permanently, the configuration information must be written to the configuration file for Class 5 environment variable profile/etc/profile/etc/profile.d/*.sh~/.bash_profile (home directory is in effect for the current user) ~/.BASHRC (home directory Valid for the current user)/ETC/BASHRC
Environment variables modified to re-login to take effect can take advantage of the source configuration file can divine login process

Linux environment variables