Linux environment variable set env export

The linux environment variable set env export is used to describe the set, env, and export commands, difference [root @ localhost root] # a = test [root @ localhost root] # echo $ atest [root @ localhost root] # set | grep aa = test [root @ localhost root] # env | grep a [root @ localhost root] # export a [root @ localhost root] # env | grep aa = testset display the current shell variable, including the current user's variable env display the current user's variable export display the shell variable currently exported to the user variable each shell has its own unique variable, which is different from the user variable. The current user variables are irrelevant to what shell you use, no matter what shell you use. For example, HOME, SHELL, and other variables, but shell's own variables, different shells are different, such as BASH_ARGC, BASH, and so on. These variables are only displayed in set and are unique in bash. When an export parameter is not added, it shows which variables are exported as user variables, because a shell's own variable volume can be changed to a user variable through export "export.