Linux system administrator, job interview questions (1)

1. What is CVS and list some of its commands? What is SVN?
CVS is Concurrent Version System.  Version control system software keeps track of all work and all changes in a set of files, and allows several  developers (potentially widely separated in space and/or time) to collaborateSome of its command are:


CVS add
cvs checkout
cvs update
cvs remove
cvs commit

Subversion (SVN) is a version control system. It allows users to keep track of  changes made to any type of electronic data, typically source code, web pages or design documents. Subversion is currently a popular alternative to CVS and quite popular software.


2. What is NFS?

NFS is Network File System, allowing a user on a client computer to access files  over a network in a manner similar to how local storage is accessed.

3.How can you  access CDROM?

As root, you can mount the CDROM with a command like this:

mount -t auto /dev/cdrom /mnt/cdrom

If this works, the contents of your CD appears in the directory /mnt/cdrom

4. What are RPM and YUM package management? 

The RPM Package Manager (RPM) is a powerful command line  driven package management system capable of installing, uninstalling, verifying, querying, and updating
computer software packages .

Installing a RPM package Using rpm -ivh
Query all the RPM Packages using rpm -qa
Query a Particular RPM Package using rpm -q
Upgrading a RPM Package using rpm -Uvh
Uninstalling a RPM Package using rpm -e
Verifying all the RPM Packages using rpm -va
 
For YUM:
Display list of updated software: yum list updates

To download and install all updates: yum update
List all installed packages, enter:

# rpm -qa
# yum list installed
Find out if httpd package installed or not, enter:
# rpm -qa | grep httpd*
# yum list installed httpd
To check for and update httpd package, enter:
# yum update httpd
Search httpd and all matching perl packages, enter:
# yum list httpd
# yum list perl*
Install package called httpd:
# yum install httpd

Remove package called httpd
# yum remove httpd

Display the list of available packages
# yum list all



Display what package provides the file:

You can easily find out what RPM package provides the file.
For example find out what provides the /etc/passwd file:

# yum whatprovides /etc/passwd

5. How to configure wireless in Linux?

For command line:
For example, if your wireless NIC is named eth0 and your managed network's ESSID is homenet, then the commands would be.

iwconfig eth0 mode Managed
iwconfig eth0 essid homenet


For system:

 Debian / Ubuntu

In Debian / Ubuntu systems configuration requires the addition of a valid wireless-essid parameter to the /etc/network/interfaces file.

#
# File: /etc/network/interfaces
#

# The primary network interface
auto eth1
iface eth1 inet static
        address 192.168.1.100
        netmask 255.255.255.0
        wireless-essid homenet

auto eth0
iface eth0 inet dhcp
        wireless-essid jamrock

In this example interface eth1 uses an ESSID of homenet while interface eth0 uses an ESSID of jamrock.

 Fedora / RedHat

With Fedora / RedHat, wireless configuration will require some additional statements in your NIC (Network Interface Controller) configuration files.

1. Configure your /etc/sysconfig/network-scripts/ifcfg-eth0 file normally as if it were a regular Ethernet NIC.
add following:

#
# Wireless configuration
#
TYPE=Wireless
MODE=Managed
ESSID=homenet
RATE=54Mb/s
 
6. HowTo: Upgrade Red Hat Enterprise Linux to v5.5?
Register your system with RHN for RHEL / CentOS Linux version 5.x or above.
 rhn_register

# uname -a
# yum update
Reboot the server:
# reboot
Verify everything is working:
# uname -a
See /etc/redhat-release file, enter:
# cat /etc/redhat-release

Red Hat Enterprise Linux Server release 5.5 (Tikanga)

Verify that ports are open and all services are running:
# netstat -tulpn
# tail -f /var/log/messages
# tail -f /path/to/log/file