how to Enable EPEL Repository for RHEL linux.

how to Enable EPEL Repository for RHEL linux.
EPEL (Extra Packages for Enterprise Linux)
ref : linux 

install tomcat on linux

install tomcat

go to /temp dir
sudo wget http://redrockdigimark.com/apachemirror/tomcat/tomcat-7/v7.0.69/bin/apache-tomcat-7.0.69.tar.gz

2) unzip file
tar xzf apache-tomcat-7.0.69.tar.gz

3) move the folder to tomcat7

mv apache-tomcat-7.0.69 /usr/local/tomcat7

4) start the tomcat server.
go to the ./bin/startup.sh

output :
cmd : ./bin/startup.sh
Using CATALINA_BASE:   /usr/local/tomcat7/apache-tomcat-7.0.69
Using CATALINA_HOME:   /usr/local/tomcat7/apache-tomcat-7.0.69
Using CATALINA_TMPDIR: /usr/local/tomcat7/apache-tomcat-7.0.69/temp
Using JRE_HOME:        /usr/java/jdk1.8.0_45/jre
Using CLASSPATH:       /usr/local/tomcat7/apache-tomcat-7.0.69/bin/bootstrap.jar:/usr/local/tomcat7/apache-tomcat-7.0.69/bin/tomcat-juli.jar
Tomcat started.

5) set up user account in conf/tomcat-users.xml.

<!-- user manager can access only manager section -->
<role rolename="manager-gui" />
<user username="manager" password="abc" roles="manager-gui" />

<!-- user admin can access manager and admin section both -->
<role rolename="admin-gui" />
<user username="admin" password="def" roles="manager-gui,admin-gui" />


6) change the port to 8082

go to conf/server.xml  and change the default port from 8080 t0 8082

 <Connector port="8082" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />

7) connect to tomcat :
http://xx.xxx.xxx.xxx:8082/manager/html

set the java path permanently in linux

c) set the java path

export JAVA_HOME=/usr/java/jdk1.8.0_45

d) Setup JRE_HOME Variable

export JRE_HOME=/usr/java/jdk1.8.0_45/jre

e) Setup PATH Variable

export PATH=$PATH:/usr/java/jdk1.8.0_45/bin:/usr/java/jdk1.8.0_45/jre/bin

environment variable :

/etc/environment

to set the variable permanently.

go to directory
/etc
open profile.
cmd : vi profile

set all the variable at the bottom of the pofile.
check from new command window weather you are able to see the path.

intsall nodejs in rhel linux .

intsall nodejs in rhel linux .
command :
1) sudo rpm -ivh epel-release-7-6.noarch.rpm
2) sudo yum install npm
3) node --version

find puppet intalled in rhel linux

how to find the version  of puppet intalled in rhel linux

cmd : rpm -qa | grep puppet

puppetlabs-release-7-12.noarch
puppet-...x.noarch
puppet-server-x.x.x.x.noarch

know the linux version

how to know the linux version.
for kernel level.
1) uname -a
2) to know the redhat version then use.
cmd : cat /etc/redhat-release.

remove directory in linux

Remove directory in linux.

delete directory
cmd :  rm -r mydir

delete directory and files with in directory

cmd :  rm -r mydir


REF : computerhope

open a port in linux using firefall-cmd

open a port in linux using firefall-cmd.

before running the command install firewalld package.

1) install the firewalld on linux
cmd : yum install firewalld
2) check status.
cmd : systemctl status firewalld
if it is not enable, enable it.
cmd : systemctl enable firewalld
3) if it not started start it.
cmd : systemctl start firewalld

4) stop the firewall
cmd : service firewalld stop



Now we have to open the port which will visible to public
open port :
cmd : firewall-cmd --zone=public --add-port=8090/tcp --permanent

reload the service :
firewall-cmd --reload

check whether the port was added to ipatables rules:
iptables-save | grep 8090

REF :
1) liquidweb
2) linuxconfig

linux export not a valid identifier

-bash: export: `=': not a valid identifier

Hen making an export. remove the in between spaces.

export JAVA_HOME = "/usr/...". (with spaces)

export JAVA_HOME="/usr/profile" (without spaces).

Find Out Which Process Is Listening Upon a Port

Find Out Which Process Is Listening Upon a Port

for check what port the tomcat server is using

use : netstat – a command-line tool that displays network connections, routing tables, and a number of network interface statistics.

ex : netstat -tulpn

Get a list of the installed services in linux

Get a list of the installed services in linux

To get a list of the installed services on the shell, you may use this command linux

chkconfig --list

Failed to connect to repository : Could not init /tmp/hudson

Failed to connect to repository : Could not init /tmp/hudson

1) There's no such executable git in PATH: /sbin, /usr/sbin, /bin, /usr/bin.
In the jenkins job section.
Advanced...
Source Code Management.
got git.
2) Failed to connect to repository : Could not init /tmp/hudson

solution : please install git(as below ) or provide the git exe file path (/usr/bin/git).  

Install git on linux.

command : sudo yum install git-all

ref : https://git-scm.com/book/en/v2/Getting-Started-Installing-Git

now check the git version.
cmd : git --version

Know tomcat version on linux

Know tomcat version on linux

sudo rpm -qa | grep tomcat

output : tomcat-7.x.x.

Install maven on redhat linux

Install maven on redhat  linux

wget : to retrieve content from server

REF : maven mirror

1) wget http://mirror.olnevhost.net/pub/apache/maven/binaries/apache-maven-3.2.1-bin.tar.gz

1.1)
create the apache-maven if not exist.
command :
sudo mkdir -m a=rwx /usr/local/apache-maven

1.2) Go to apache-maven directory and execute the command.
maven

1.3) extract the file
command : tar xvf apache-maven-3.2.1-bin.tar.gz

1.4) export the path
1.4.1) export M2_HOME=/usr/local/apache-maven/apache-maven-3.2.1
1.4.2)export M2=$M2_HOME/bin
1.4.3) export PATH=$M2:$PATH

1.5) verify maven version
mvn -version

output :

Maven home: /usr/local/apache-maven/apache-maven-3.2.1
Java version: 1.8.0_45, vendor
Java home: /usr/java/jdk1.8.0_45/jre
Default locale:
OS name: "linux",

REF : 1) stackoverflow
           2) linux