Ubuntu /etc/security/limits.conf 不生效问题

一、问题描述

修改 /etc/security/limits.conf ，重启之后不生效

内容如下：

* soft nofile
* hard nofile
root soft nofile
root hard nofile
* soft nproc
* hard nproc
root soft nproc
root hard nproc 

二、解决问题

根据网上资料的说法有几种

1. 修改 /etc/ssh/sshd_config

开启这2项

UsePAM yes
UseLogin yes

2. 以下几个文件

/etc/pam.d/login
/etc/pam.d/su
/etc/pam.d/sshd

确保开启了pam_limits.so

session    required   pam_limits.so

3. 重启系统

注意：修改了/etc/security/limits.conf ，必须要重启，才能生效。

以上几个，都测试了一下，open files没有生效！max user processes倒是生效了

root@ubuntu:~# ulimit -a
core file size          (blocks, -c)
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e)
file size               (blocks, -f) unlimited
pending signals                 (-i)
max locked memory       (kbytes, -l)
max memory size         (kbytes, -m) unlimited
open files                      (-n)
pipe size            ( bytes, -p)
POSIX message queues     (bytes, -q)
real-time priority              (-r)
stack size              (kbytes, -s)
cpu time               (seconds, -t) unlimited
max user processes              (-u)
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

最后终于找到原因了，是因为 内核参数没有配置

# 编辑配置文件
vi /etc/sysctl.conf

fs.nr_open = 

# 重新加载
sysctl -p

再次重启，效果如下：

root@ubuntu:~# ulimit -a
core file size          (blocks, -c)
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e)
file size               (blocks, -f) unlimited
pending signals                 (-i)
max locked memory       (kbytes, -l)
max memory size         (kbytes, -m) unlimited
open files                      (-n) 2048576
pipe size            ( bytes, -p)
POSIX message queues     (bytes, -q)
real-time priority              (-r)
stack size              (kbytes, -s)
cpu time               (seconds, -t) unlimited
max user processes              (-u)
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

本文参考链接：

https://blog.51cto.com/jonyisme/1919075