linux设置最大打开文件数

一、查看当前用户对进程打开文件最大数的限制

$ ulimit -a | grep open

二、系统对进程打开文件最大数是如何限制的

先来看man的一段解析：

    /proc/sys/fs/file-max
           This file defines a system-wide limit on the number of open files for all processes.  (See also setrlimit(),  which  can  be
           used by a process to set the per-process limit, RLIMIT_NOFILE, on the number of files it may open.)  If you get lots of error
           messages in the kernel log about running out of file handles (look for "VFS: file-max limit <number> reached"), try  increas‐
           ing this value:  

               echo  > /proc/sys/fs/file-max  

           The kernel constant NR_OPEN imposes an upper limit on the value that may be placed in file-max.  

           If  you  increase  /proc/sys/fs/file-max,  be  sure  to  increase  /proc/sys/fs/inode-max  to  -  times  the  new  value of
           /proc/sys/fs/file-max, or you will run out of inodes.  

           Privileged processes (CAP_SYS_ADMIN) can override the file-max limit.  

（1）修改系统总限制(永久生效)

echo "" > /proc/sys/fs/file-max  

（2）修改进程的软硬限制(永久生效)

vi /etc/security/limits.conf  

添加：

* soft nofile
* hard nofile   

注：*表示所有用户都生效

三、重启shell，校验配置是否生效

$ ulimit -a | grep open

原文出自：http://blog.csdn.net/daiyudong2020/article/details/77828959