Installing EPEL Repository on CentOS

EPEL stands for Extra Packages for Enterprise Linux. This is a massive collection of packages that are very useful for the building of many modern stacks and include many tools for the running and maintenance of systems. The homepage of EPEL is here: http://fedoraproject.org/wiki/EPEL. You can browse the package set using repoview: EPEL 6: i386, x86_64, ppc64, sources EPEL 5: i386, x86_64, ppc, sources Installing on…

Setting hostname

#vim /etc/sysconfig/network Use something like HOSTNAME=testarossa.maranello.local to overwrite the default name and domain of the server. e.g. NETWORKING=yes HOSTNAME=testarossa.maranello.local To avoid rebooting issue the following : hostname  testarossa.maranello.local That will set it for the current  session.      

Monitoring connections

To monitor TCP and UDP connections the following command is very useful: netstat -t -u to have a continuous update use the watch command: watch netstat -t -u There is a much stronger tool for real time analysis called iptraf. It is quite self explanatory : at command line run iptraf This tool has many functions…

Fixing Warning: RPMDB altered outside of yum

What does it mean? The yum message “Warning: RPMDB altered outside of yum.” or, as the yum message said for a few months, “Warning: RPMDB has been altered since the last yum transaction.” means some application has altered the rpm database (installed or removed a package) without going through the Yum APIs. This is almost…

Setting up NTP server

Setting up NTP is very important for a host of application especially clusters and applications like DBs requiring all the servers to be critically time-wise synced. Install NTP on Red Hat and CentOS 6 $ yum install ntp $ chkconfig ntpd on $ ntpdate pool.ntp.org $ service ntpd start Install NTP on Ubuntu $ apt-get…

Setup default gateway with route command Linux

Display default route The following three commands display the current routing table: # route Output: Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.1.0 * 255.255.255.0 U 0 0 0 ra0 default dsl-router 0.0.0.0 UG 0 0 0 ra0 # /sbin/route Output: Kernel IP routing table Destination Gateway Genmask Flags Metric…

Installing iostat in CentOS with yum

Iostat is a very powerful tool for monitoring the throughput of your storage subsystems. Especially to locate bottle necks and pinpoint possible upgrade scenarios. Not immediately visible here is how to install it on Centos 5.x and 6.x. We shall use the whatprovides tool in yum to locate the packages that provide iostat  

Installing vim editor.

To install vim [root@testarossa-00-0c-29-47-8f-35 ~]# yum whatprovides vim-enhanced Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * base: mirror.crazynetwork.it * epel: fr2.rpmfind.net * extras: mirror.crazynetwork.it * updates: mirror.crazynetwork.it 2:vim-enhanced-7.0.109-7.el5.i386 : A version of the VIM editor which includes : recent enhancements. Repo : base Matched from: [root@testarossa-00-0c-29-47-8f-35 ~]# yum install vim-enhanced-7.0.109-7.el5.i386 Loaded plugins: fastestmirror…

VIM cheat sheet

< The list of Vim commands > Working with files Vim command Action :e filename Open a new file. You can use the Tab key for automatic file name completion, just like at the shell command prompt. :w filename Save changes to a file. If you don’t specify a file name, Vim saves as the file name…