CentOS 7 Gnome installation

when you installed the CentOS  7  operating system,  if you choose the minimal installation, then GUI interface will not be installed by defalut.  but after you worked in this mininal centos 7 system, you wanna to back to graphic user interface, the easy way is to install one GUI package, two GUI programs you can choose: Gnome or Kde. in this post, you will see how to install Gnome package under CentOS 7 operating system.

 CentOS 7  Gnome installation

Before you installed the Gnome package, you’d better to check the installation source is normal, As we need to use it to install gnome package by  yum command, and this command use this package source to download gnome package. issue the followind command:

 [root@elite ~]# yum check-update
Loaded plugins: fastestmirror, shaman
Loading mirror speeds from cached hostfile
 * cl-base: de-proxy.cl-mirror.net
 * cl-updates: de-proxy.cl-mirror.net
ez-templates                                                                                                                                                            | 1.1 kB     00:00   
ez-templates-32                                             

Using yum command to install gnome package, issue the following command:

1	[root@elite ~]#   yum groupinstall "GNOME Desktop" "Graphical Administration Tools"

Updating runlevel of system
If you want to make the system  to automatically enter into the graphical interface at boot time, you must change the runlevel value, issue the following command:

1	[root@elite ~]# sudo  ln -sf /lib/systemd/system/runlevel5.target /etc/systemd/system/default.target

reboot the system

> 

after you reboot the system , the system will enter into the Gnome GUI interface automatically.

Nagios HTTP WARNING: HTTP/1.1 403 Forbidden

Nagios HTTP WARNING: HTTP/1.1 403 Forbidden

========================================

Whenever we  setup the nagios server we mostly get this error “Nagios HTTP WARNING: HTTP/1.1 403 Forbidden”.
In dashboard it shows alert on localhost i.e our own newly set up nagios server

===================================

To solve this alert, create a index.html file inside /var/www/html in server

touch /var/www/html/index.html

Restart the httpd and nagios service. Even without doing this it will clear the alert after a few minutes.

/etc/init.d/nagios restart

/etc/init.d/httpd restart

Wait for a few minutes the alert will be gone.
====================================
 

Fix 'thread.error: can’t start new thread' error while yum update

Fix 'thread.error: can’t start new thread' error while yum update

Sometimes when we run 'yum update' or try to install or update softwares using yum, you will get 'thread.error: can’t start new thread ' error.

=============================================================

File "/usr/lib/yum-plugins/fastestmirror.py", line 333, in get_mirrorlist
    self._poll_mirrors()
  File "/usr/lib/yum-plugins/fastestmirror.py", line 376, in _poll_mirrors
    pollThread.start()
  File "/usr/lib/python2.4/threading.py", line 416, in start
    _start_new_thread(self.__bootstrap, ())
thread.error: can't start new thread

======================================================================= 

This error is due to the inadequate memory for yum operation. This occurs due to Yum’s fastest-mirror plugin. So, if you have a low end VPS then you may see this error often. To solve this just disable that plugin.

You can disable this plugin in 2 ways :

Login using root issue and issue this command.

[root@elite ~]# vi /etc/yum/pluginconf.d/fastestmirror.conf

And change this line
enable=1
to
enable=0

OR

Login using root issue and issue this command.

[root@elite ~]# yum --disableplugin=fastestmirror update

This plugin is used to find the fastest mirrors/sources available for the software so that the update/install process is quicker. To re-enable the plugin, just run the command.

[root@elite ~]# yum --enableplugin=fastestmirror update

OR

change enable=1 in fastestmirror.conf file