Limits on Number of Files and Processes (ulimit)

  1. user can open file that size < ??
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ulimit -u

# result : 1024

  1. user can create process(nproc)

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    # select all user create process
    ps h -Led -o user | sort | uniq -c | sort -n

    # select one user create process
    ps -o nlwp,pid,lwp,args -u chen | sort -n

  2. update process number

if command print error, that can change user can process number

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Cannot create GC thread. Out of system resources  
java.lang.OutOfMemoryError: unable to create new native thread

  • 需要先看linux操作系统内核版本，通过uname -a查看内核版本，因为2.6版本的内核默认是在/etc/security/limits.d/90-nproc.conf里的配置会覆盖/etc/security/limits.conf的配置

uname -a

Linux hadoop219 2.6.32-431.el6.x86_64 #1 SMP Fri Nov 22 03:15:09 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

  • 修改配置文件

vi /etc/security/limits.d/90-nproc.conf

注释掉 * soft nproc 1024

  • 修改limits.conf文件

vi /etc/security/limits.conf
添加

soft nproc 655350

  • 在控制台执行(修改这个不需要重启)

ulimit -u 655350

5.检查下是否生效，在控制台切到该用户下

ulimit -u

ssh

add ssh key learn address

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#db
ssh-keygen -t rsa -b 4096

# generat ssh key
ssh-copy-id root@192.168.4.214

DNS

NTP

NTP(network time protocol)

最后更新： 2020年02月10日 21:02

原始链接： https://chenadminchen.github.io/2019/11/22/linux-command-2/

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