如题：
修改这个文件就行了：/etc/security/limits.conf
查看当前配置的方法：
1. 找到httpd的pid（中间那三个apache的）
[root@server-tong-1 ~]# ps -ef |grep httpdroot 1234 1 0 03:21 ? 00:00:00 /usr/sbin/httpd -DFOREGROUNDapache 1235 1234 0 03:21 ? 00:00:00 /usr/sbin/httpd -DFOREGROUNDapache 1236 1234 0 03:21 ? 00:00:00 /usr/sbin/httpd -DFOREGROUNDapache 1237 1234 0 03:21 ? 00:00:00 /usr/sbin/httpd -DFOREGROUNDapache 1239 1234 0 03:21 ? 00:00:00 /usr/sbin/httpd -DFOREGROUNDroot 1537 1210 0 03:28 pts/0 00:00:00 grep --color=auto httpd
2. 查看这几个进程当前使用的值
[root@server-tong-1 ~]# cat /proc/1236/limitsLimit Soft Limit Hard Limit Units Max cpu time unlimited unlimited seconds Max file size unlimited unlimited bytes Max data size unlimited unlimited bytes Max stack size 8388608 unlimited bytes Max core file size 0 unlimited bytes Max resident set unlimited unlimited bytes Max processes 15072 15072 processes Max open files 1024 4096 files Max locked memory 65536 65536 bytes Max address space unlimited unlimited bytes Max file locks unlimited unlimited locks Max pending signals 15072 15072 signals Max msgqueue size 819200 819200 bytes Max nice priority 0 0 Max realtime priority 0 0 Max realtime timeout unlimited unlimited us
3. 查看系统允许修改的最大值，以及用户名
[root@server-tong-1 ~]# cat /etc/shadow |grep apaapache:!!:17833::::::[root@server-tong-1 ~]# cat /proc/sys/fs/nr_open 1048576
查到，limit可以使用的最大值是1048576，用户名是apache
另外，需要提到的一点，我曾经尝试直接将这个值设置成unlimited, 结果导致了root无法登录。【大哭～～】，后来想办法进去之后，查看到报错如下：【tag：修改limit.conf之后 ssh失败 root无法登录 OS无法登录】
546 Dec 10 02:44:03 server-tong-1 login: pam_limits(login:session): Could not set limit for ‘nofile‘: Operation not permitted547 Dec 10 02:44:03 server-tong-1 login: pam_unix(login:session): session opened for user root by LOGIN(uid=0)548 Dec 10 02:44:03 server-tong-1 login: Permission denied549 Dec 10 02:44:15 server-tong-1 login: pam_limits(login:session): Could not set limit for ‘nofile‘: Operation not permitted550 Dec 10 02:44:15 server-tong-1 login: pam_unix(login:session): session opened for user root by LOGIN(uid=0)551 Dec 10 02:44:15 server-tong-1 login: Permission denied552 Dec 10 02:44:42 server-tong-1 login: pam_limits(login:session): Could not set limit for ‘nofile‘: Operation not permitted553 Dec 10 02:44:42 server-tong-1 login: pam_unix(login:session): session opened for user root by LOGIN(uid=0)554 Dec 10 02:44:42 server-tong-1 login: Permission denied555 Dec 10 02:44:55 server-tong-1 login: pam_unix(login:auth): check pass; user unknown556 Dec 10 02:44:55 server-tong-1 login: pam_unix(login:auth): authentication failure; logname=LOGIN uid=0 euid=0 tty=tty1 ruser= rhost=557 Dec 10 02:44:57 server-tong-1 login: FAILED LOGIN 1 FROM tty1 FOR (unknown), User not known to the underlying authentication module558 Dec 10 02:45:03 server-tong-1 login: pam_limits(login:session): Could not set limit for ‘nofile‘: Operation not permitted559 Dec 10 02:45:03 server-tong-1 login: pam_unix(login:session): session opened for user root by LOGIN(uid=0)560 Dec 10 02:45:03 server-tong-1 login: Permission denied561 Dec 10 02:50:01 server-tong-1 crond[14616]: pam_limits(crond:session): Could not set limit for ‘nofile‘: Operation not permitted562 Dec 10 03:00:01 server-tong-1 crond[14649]: pam_limits(crond:session): Could not set limit for ‘nofile‘: Operation not permitted563 Dec 10 03:00:20 server-tong-1 sshd[784]: Received signal 15; terminating.
4. 准备就绪后，我们现在来修改limit.conf文件吧！追加两行配置如下，并重启OS
[root@server-tong-1 ~]# tail -n3 /etc/security/limits.conf apache hard nofile 1048576apache soft nofile 1048576# End of file[root@server-tong-1 ~]#
5. 用2中的方法查看修改是否成功。
完！
