Centos-7

Centos -7 [version 4.3]

To edit the hostname of the centos7

nmtui à edit the hostname window will appear…

To enable internet based dhcp, you will need to set onboot=yes in below file
nano /etc/sysconfig/network-scripts/ifcfg-enp03s

then doà service network restart [command] if okay then your internet is up..

check ifconfig also to know the ip address..

To install the GUI on centos os with command line shell only
  • yum groupinstall “GNOME Desktop” “Graphical Administration Tools”
  • Startx to move to gui
  • To set the default on boot to gui..

ln -sf /lib/systemd/system/runlevel5.target /etc/systemd/system/default.target

To List port being utilized by services running on centos

lsof -Pnl +M -i

To change firewall setting in the centos7 machine

To change firewall setting… there is good way to do in centos 7

System-config-firewall-tui [if this utility not available then you could download it by below command]

Yum install system-config-firewall-tui

Lets say you get an error that firwalld is active and you should use firewall-cmd command

Below is the command to use…

Firewall-cmd –-zone=public –-add-port=9090/tcp –permanent [to enable port 9090]

Firewall-cmd –reload [to reload the ip tables]

How to solve the problem where guest OS machine is hosting a web application and not able to access by host machine or any other guest OS machine like windows , Ubuntu, Centos 7 etc..
  • Ensure both guest OS and host VM\otherVM is connected through Bridge adapter
  • Ensure both can ping each other.
  • Ensure what port is need to be open on the guest OS is open. For instance centos require port explicitly to be open for all incoming traffic. For that use the below commend.
  • Below is the command to use…

Firewall-cmd –-zone=public –-add-port=9090/tcp –permanent [to enable port 9090]

  • Firewall-cmd –reload [to reload the ip tables
How to set Java variable environment

Follow the given below steps (Replace the version no. as per your new Java version installed in your system)

Step1 : Go to /etc and then open the “profile” text file using an editor like Vi, Emacs or Nano.

Step 2 :  Type below command

export JAVA_HOME=/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65-2.5.1.2.el7_0.x86_64 [replace 1.7 with 1.8]

Read more : http://www.ehow.com/how_8424526_set-java-home-centos.html

  • Ensure below command is typed in the editor so that it is in effect immediately..

export JAVA_HOME=/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65-2.5.1.2.el7_0.x86_64

Install RPM Packages

RPM packages typically have file names like foo-1.0-1.i386.rpm. The file name includes the package name (foo), version (1.0), release (1), and architecture (i386). To install a package, log in as root and type the following command at a shell prompt:

rpm -ivh foo-1.0-1.i386.rpm [install]

rpm -Uvh foo-1.0-1.i386.rpm [upgrade]

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