process是OS邏輯排程執行的基本單位。為了管理process,OS會將process分組管理,**session和process group (PG)**就是process群組的單位。一個session可包含多個process group,一個process group可以包含多個process。session/PG有以下性質:
每個session/PG都會有一個leader,通常是該群集中第一個process
每個session/PG都會有一個id,由該群集中第一個process的PID決定
每個session可以配給一個terminal
一個session中,terminal會被attach到其中一個process group
被attach terminal的process group給名詞叫foreground process group
$ ssh-keygen -t rsa -C "email@example.com" Generating public/private rsa key pair. Enter file in which to save the key (/home/linyunwen/.ssh/id_rsa): Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /home/linyunwen/.ssh/id_rsa Your public key has been saved in /home/linyunwen/.ssh/id_rsa.pub The key fingerprint is: SHA256:2JmjfMInqjqXcEzoacXw7k9E0mH6SloJ4oDwnHqGu3U [email@gmail.com](mailto:email@gmail.com) The key's randomart image is: +---\[RSA 3072\]----+ |. o | |o+ .+ . | ... |o+ooE.* o | |.ooo.. = | |o+..o. | +----\[SHA256\]-----+