https://www.cyberciti.biz/faq/linux-increase-the-maximum-number-of-open-files/linux
https://serverfault.com/questions/122679/how-do-ulimit-n-and-proc-sys-fs-file-max-differide
file-max是全局約束。ui
ulimit -n中是對某個用戶的每一個進程的約束(open files)。unix
ulimit -aH是hard limitserver