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(2),  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 100000 > /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  3-4  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 "655350" > /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 655350
* hard nofile 655350

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

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