计算机技术学习记录

Blog

  • 查找spring可配置项

    spring 配置文件有哪些可配置项, 可以从官网查询

    https://docs.spring.io/spring-boot/docs/current/reference/html/application-properties.html

  • 如何使用nologin用户执行命令

    nologin 用户执行命令

    [root@node1 ~]# ls -al /tmp/qemu-user-test
ls: cannot access '/tmp/qemu-user-test': No such file or directory

[root@node1 ~]# su -s /bin/bash -c 'echo "i am nologin user." > /tmp/qemu-user-test' qemu

[root@node1 ~]# ls -al /tmp/qemu-user-test
-rw-r--r-- 1 qemu qemu 19 Jan 31 11:29 /tmp/qemu-user-test

[root@node1 ~]# cat /tmp/qemu-user-test
i am nologin user.

  • 检查ip冲突的方法

    使用arping检查ip冲突.

    [root@node1 ~]# arping -I enp4s0f0  192.168.11.3
ARPING 192.168.11.3 from 192.168.12.196 enp4s0f0
Unicast reply from 192.168.11.3 [18:C0:4D:1D:AA:7C]  0.683ms
Unicast reply from 192.168.11.3 [18:C0:4D:1D:AA:7C]  0.551ms
Unicast reply from 192.168.11.3 [18:C0:4D:1D:AA:7C]  0.562ms
Unicast reply from 192.168.11.3 [18:C0:4D:1D:AA:7C]  0.548ms

    如果返回的mac 地址有多个, 说明这个局域网出现ip冲突.

  • centos7编译打包keepalived-2.2.8

    keepalived 虚拟机环境内存泄露

    centos7 自动的keepalived 版本是1.3.5 , 在虚拟机下运行时存在vrrp 导致的内存泄漏.

    Memory leak on raw vrrp socket ? #839

    下载编译打包 keepalived 2.2.8

     yum install rpm-build
 yum install wget
 yum install kernel-devel
 yum install rpm-build make gcc openssl-devel popt-devel kernel-devel ipvsadm
 yum install aclocal autoheader automake autoreconf
 yum install net-snmp-devel
 yum install net-snmp-devel -y
 yum install openssl-devel
 yum install kernel-headers
 yum install gcc rpm-build rpm-devel rpmlint make coreutils diffutils patch rpmdevtools
 yum install net-snmp-devel
 yum install libnl-devel
 yum install net-snmp net-snmp-utils net-snmp-libs
 yum install  kmod-devel  systemd-devel


    rpmdev-setuptree

cp keepalived-2.2.8.tar.gz rpmbuild/SOURCES/

#下载keepalived 2.2.8
wget https://www.keepalived.org/software/keepalived-2.2.8.tar.gz  --no-check-certificate
tar xf keepalived-2.2.8.tar.gz

cd keepalived-2.2.8
#configure
./autogen.sh
./configure  --enable-snmp
#compile and create rpm
rpmbuild -ba keepalived.spec

    keepalived-2.2.8-1.el7.x86_64.rpm 位置

    [root@d1918be059ac ~]# find rpmbuild/ |grep rpm$
rpmbuild/RPMS/x86_64/keepalived-2.2.8-1.el7.x86_64.rpm
rpmbuild/RPMS/x86_64/keepalived-debuginfo-2.2.8-1.el7.x86_64.rpm
rpmbuild/SRPMS/keepalived-2.2.8-1.el7.src.rpm

#安装
yum install keepalived-2.2.8-1.el7.x86_64.rpm

  • 统计linux系统进程内存使用百分比

    打印一次所有进程情况

    top -b -n 1

    忽略前面8行

    tail -n +8

    统计

    top -b -n 1  \
|awk '{print $10}'\
|tail -n +8 \
|xargs  -i echo "{} +" \
|xargs -r \
|xargs -i python -c "print( {} 0)"

    统计2

    ps axu --sort -rss \
|awk '{print $6}'|tail -n +2 \
|xargs  -i echo "{} +"|xargs -r \
|xargs -i python -c "print( {} 0)"