Linux Useful Commands

java -version
##java version "1.7.0_51" this os old vesrion then remove it
rpm -qa| grep openjdk|xargs rpm -e --nodeps
##upload jdk to /usr/java
tar /usr/java/xzvf jdk-8u144-linux-x64.tar.gz
vim /etc/profile
export JAVA_HOME=/usr/java/jdk1.8.0_144
export
##CLASSPATH=.:$JAVA_HOME/jre/lib/rt.jar:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export PATH=$PATH:$JAVA_HOME/bin
source /etc/profile
java -version

Bash

4. Yum install or replace

##1. 1. First, delete the original yum of redhat
rpm -aq | grep yum | xargs rpm -e --nodeps
rpm -aq | grep python-iniparse | xargs rpm -e --nodeps 
rpm -aq | grep yum
rpm -aq | grep python-iniparse
##2. get Yum installation
##3. Install the downloaded rpm package
rpm -ivh python-iniparse-0.4-9.el7.noarch.rpm
rpm -ivh yum-*.rpm # If anything is lacking during installation, find it in the downloaded software and install it
## 4. Create the file /etc/yum. repos. d/CentOS-Base. repo
touch /etc/yum.repos.d/CentOS-Base.repo
##copy paste in CentOS-Base.repo
[base]
name=CentOS-$releasever - Base
baseurl=https://mirrors.aliyun.com/centos/7/os/$basearch/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos/7/os/x86_64/RPM-GPG-KEY-CentOS-7
#released updates
[updates]
name=CentOS-$releasever - Updates
baseurl=https://mirrors.aliyun.com/centos/7/updates/$basearch/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos/7/os/x86_64/RPM-GPG-KEY-CentOS-7
[extras]
name=CentOS-$releasever - Extras
baseurl=https://mirrors.aliyun.com/centos/7/extras//$basearch/
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/centos/7/os/x86_64/RPM-GPG-KEY-CentOS-7
[centosplus]
name=CentOS-$releasever - Plus
baseurl=https://mirrors.aliyun.com/centos/7/centosplus//$basearch/
gpgcheck=1
enabled=0
#######################
yum clean all
Yum makecache

Shell

5. SNMP service

rpm -qa|grep snmp
#If net-snmp-5.7. 2-1 is not available, it indicates that it has not been installed;
##otherwise, it indicates that it has been successfully installed
## If it is uninstalled, execute
rpm -e net-snmp-XXX --nodeps
yum list | grep net-snmp
yum -y install net-snmp*

## Modify snmpd.conf sed command
Cp /etc/snmp/snmpd. conf /etc/snmp/snmpd. conf. bak #First backup the configuration file
Sed -i '41 s/public/cmsnmp/' /etc/snmp/snmpd. conf #modify line 41, public is cmsnmp
sed -i '207s/#proc mountd/proc mountd/' /etc/snmp/snmpd.conf
sed -i '210s/#proc ntalkd 4/proc ntalkd 4/' /etc/snmp/snmpd.conf
sed -i '213s/#proc sendmail 10 1/proc sendmail 10 1/' /etc/snmp/snmpd.conf
sed -i '272s/#exec echotest/exec echotest/' /etc/snmp/snmpd.conf
sed -i '323s/#disk/disk/' /etc/snmp/snmpd.conf
sed -i '352s/#load 12 14 14/load 12 14 14/' /etc/snmp/snmpd.conf
sed -i '/.1.3.6.1.2.1.1/i\view systemview included .1' /etc/snmp/snmpd.conf
#Match to the string ". 1. 3. 6. 1. 2. 1. 1", insert a line of content "view
systemview included . 1" before it 
# Confirm the modification is successful:
cat /etc/snmp/snmpd.conf | grep -E "cmsnmp|proc mountd|proc ntalkd|proc sendmail|exec
echotest|load 12|view systemview"

Shell

5.2 Start net-snmp

systemctl restart snmpd.service
ps -ef | grep snmpd

Bash

5.3 Verify net-snmp

## 1 Verify from the local client side
snmpget -v 1 -c cmsnmp localhost sysUpTime. 0 # here localhost can also be replaced by local IP
snmpwalk - v 2 c - c cmsnmp - m ALL localhost . 1. 3 | more # here localhost can also be replaced by local IP
#### 2 Verify it from the snmp server side

Bash

6. FTP install

6.1 steps

a) Check if it is installed: rpm -qa|grep vsftpd

b) Use yume to install vsftpd: yum install vsftpd

c) After the installation is complete, set power-on self-start: chkconfig vsftpd on

d) Turn off the firewall systemctl stop firewalld. service

e) Configure ftp information

mv /etc/vsftpd/vsftpd.conf /etc/vsftpd/vsftpd.conf_bak
grep -v "#" /etc/vsftpd/vsftpd.conf_bak > /etc/vsftpd/vsftpd.conf

Bash

f) Start the service: systemctl start vsftpd

g) Check if the ftp port is listening: netstat -tl

h) Create the ftp directory: mkdir /home/ftp

i) Assign permissions to the directory:

chmod -R 777 /home/ftp
chgrp -R ftp /home/ftp

Bash

j) Create user:

useradd -d /home/ftp/scc -g ftp -s /sbin/nologin scc
passwd scc

Bash

k) Restrict access to other users

##open config file
vim /etc/vsftpd/vsftpd.conf

Bash

## edit config file
local_root=/home/ftp/ #User login path
chroot_local_user=YES #lock the user to the respective directory as the root directory
user_config_dir=/etc/vsftpd/userconfig #user configuration directory
################

Bash

cd /etc/vsftpd/
mkdir userconfig
cd userconfig/
vim scc
local_root=/home/ftp/scc #copy paste in file
systemctl restart vsftpd

Bash

6.2 FTP troubleshooting

getsebool -a | grep ftp # to see what is about ftp in selinux.
###########################
####Set all_ftpd_anon_write and allow_ftpd_full_access to on state
setsebool -P allow_ftpd_anon_write on
setsebool -P allow_ftpd_full_access on

#############################
systemctl restart vsftpd ##restarts the FTP service to transfer files normally

#####################################
## if ftp user cannot log in
chmod 644 /etc/shells
chmod 664 /etc/vsftpd/ftpusers
systemctl restart vsftpd

Bash

7. Docker installation

 Copy docker-20.10. 4.tgz to target host user directory.

Use the command tar -zxvf docker-20.10. 4.tgz to decompress and get the docker folder.

Move all files in the docker folder to the /usr/bin directory.

mv /user_define_path/docker/* /usr/bin/

Use the command sudo dockerd & to start the docker daemon.

Copy docker.service to /usr/lib/systemd/system/ directory.

Modify permissions: chmod -R 755 /usr/lib/systemd/system/docker.service.

Run: systemctl enable docker.service.

The start-up and restart functions of docker are configured.

8. Redis cashe database installation

8.1 installation

Set the repository address of redis and execute the command: yum install epel-release

Installing redis yum install redis

Start redis systemctl start redis

If you want to access the database remotely, you shall open firewall port.(optional)

Set Auto-start execution command on power-up chkconfig redis on

firewall-cmd --zone=public --add-port=6379/tcp –permanent
firewall-cmd --reload
firewall-cmd --list

Bash

6. To set up remote access, you need to modify the configuration file. First, find the location of the redis.config configuration file whereis redis.config then comment bind 127.0.0.1 (change password if you want)

Modify the redis. conf configuration file vim /etc/redis.conf

After the settings are completed systemctl restart redis

8.2 Test redis

Enter the redis interactive command line  redis-cli

To add data to the database set 'a' 'b’

8.3 Redis Troubleshootng

SpringBoot connects to the Redis service, DENIED Redis is running in protected mode because protected mode is enabled Soultion in Config file Modify protected-mode yes to NO

There is an authentication problem. Soultion Be Sure that the authentication password is set auth “p@ssw0rd”

9. Influxdb installation

Download the installation package influxdb-1.8. 4.x86_64.rpm to the local

wget https://dl.influxdata.com/influxdb/releases/influxdb-1.8.4.x86_64.rpm

Bash

Execute the installation in the directory where the installation package is located: 

rpm -ivh influxdb-1.8.4.x86_64.rpm

Bash

View version  influx -version

Start Up  systemctl start influxdb.service

Set Power-on self-start  systemctl enable influxdb.service

Verify curl http://localhost:8086/query?q=show+databases

Import Data influx -import -path=/root/influxdb_dump_out -precision=ns

Check if import was successful write influx in terminal . 

View created databases: show databases.

Export database (this step is not required for deployment):

influx_inspect export -datadir "/var/lib/influxdb/data" -waldir "/var/lib/influxdb/wal" -out
"influxdb_dump_out" -database "test" -start "2021-09-10T00:00:00Z"

Bash

Notes: if you want to view the influxdb database under the window system, you can download InfluxDBStudio-0.2. 0. zip, which is an installation-free software. After decompression, double-click "InfluxDBStudio.exe" and fill in the information of the influx database to connect and view.

10. Keepalive installation

yum install -y keepalived ipvsadm
ipvsadm --save > /etc/sysconfig/ipvsadm
echo 1 > /proc/sys/net/ipv4/ip_forward
systemctl enable ipvsadm
systemctl start ipvsadm
##Start-up need to configure net.ipv4.ip_forward=1 to /etc/sysctl.conf

Bash

11. Rabbitmq installation

Take the rabbitmq image: docker pull rabbitmq:3.9-management

View image id: docker image ls -a

Run the container:

docker run --name rabbitmq -d -p 15672:15672 -p 5672:5672 4b

23cfb64730, in which 4b23cfb64730 is the container id

Enter the container interactive interface: 

docker exec -it "container id" sh

Add User 

rabbitmqctl add_user admin admin
rabbitmqctl set_permissions -p / admin ".*" ".*" ".*"
rabbitmqctl set_user_tags admin administrator

Bash

open browser http://ServerIP:15672 (user :admin , password : admin)

12. The deployment and installation of mysql

Download Mysql version 5.7.31

Mariadb is already installed by the rhel system and needs to be uninstalled. Check Mariadb, code rpm -qa|grep mariadb

Uninstall Mariadb rpm-emariadb-libs-5.5.52-1.el7.x86_64--nodeps

Check if mysql is installed and delete it  rpm -aq | grep mysql

uninstall 

rpm -ev mysql-community-common-5.7.12-1.el6.x86_64 --nodeps
rpm -ev mysql-community-libs-5.7.12-1.el6.x86_64 --nodeps
rpm -ev mysql-community-server-5.7.12-1.el6.x86_64 --nodeps
rpm -ev mysql-community-client-5.7.12-1.el6.x86_64 --nodeps

Bash

Find MYSQl directory find / -name mysql

Delete MYSQL directory

rm -rf /var/lib/mysql
rm -rf /var/lib/mysql/mysql
rm -rf /usr/lib64/mysql
rm -rf /usr/share/mysql
rm -rf /usr/local/mysql
#Delete my.cnf
rm -rf /etc/my.cnf

Bash

create mysql folder mkdir -p /usr/local/mysql/

cd /usr/local/mysql/

tar -xf mysql-5.7.31-1.el7.x86_64.rpm-bundle.tar

rpm -ivh mysql-community-common-5.7.31-1.el7.x86_64.rpm
rpm -ivh mysql-community-libs-5.7.31-1.el7.x86_64.rpm
rpm -ivh mysql-community-client-5.7.31-1.el7.x86_64.rpm
rpm -ivh mysql-community-server-5.7.31-1.el7.x86_64.rpm
rpm -ivh mysql-community-devel-5.7.31-1.el7.x86_64.rpm
systemctl start mysqld
systemctl status mysqld

Bash

Login mysql -uroot -p

Change password: ALTER USER 'root'@'localhost' IDENTIFIED BY 'root';