php – What does "export CI_ENV" mean in igniter code?

What I'm trying to do is manage cron jobs by backing them up in my database and then writing a generic task that runs every minute and triggers the saved tasks in the database. database.

I found this piece of code in a code lighter library that I saw here

$ env = getenv (& # 39; CI_ENV & # 39;)
foreach ($ query-> result () as $ row) {
$ cmd = "export CI_ENV = {$ env} && {$ line-> order}";
$ output = shell_exec ($ cmd);
// do other things
}

I do not understand what this line $ cmd = "export CI_ENV = {$ env} && {$ line-> order}"; really does. I do not understand what export do the.