Linux: Too many open files in Ubuntu

Linux: Too many open files in Ubuntu

Error messages like these in the log files of MySQL or Apache:

Error: SQLSTATE[HY000]: General error: 23 Out of resources when opening file ‘/tmp/#sql_751_0.MYD’ (Errcode: 24 – Too many open files)

Solution:

Customize /etc/security/limits.conf:
root soft nofile 800000
root hard nofile 1024000

/etc/mysql/my.cnf:
open_files_limit = 1024000

then restart server