Free derivatives of Unix can be easily downloaded via the Internet. This sets Unix apart from other proprietary operating systems like Microsoft Windows. The different Unix versions and Unix-like operating systems available for download include FreeBSD, OpenBSD, Red Hat Fedora Linux, Debian Linux, Ubuntu Linux, and Sun Solaris. Those who are new to Unix or Linux can still try these operating systems by using virtual machines, without worrying about existing data or OS being affected. The user can install his/her preferred Unix version inside the virtual machine to get a Read More

umask is a Unix shell built-in command that automatically sets file permissions on newly created files. The umask command can be confusing to use because it does work as a mask. In other words, the user sets the permissions that he/she does not want in the umask. To calculate permissions that will result from specific umask values, subtract the umask from 777. Note, however, that files are not usually created with the execute permission by default, so the final permissions for files will omit the “x” permission. For example, if Read More

One of the best methods to capture a Unix terminal session is to use the `script` command. In this example we start a script session, run a couple of commands, and then use the `exit` command to stop capturing the terminal session: $ script Script started, output file is typescript $ pwd /home/will $ ps PID TT STAT TIME COMMAND 11909 p0 Ss 0:00.05 -bash (bash) 25622 p0 S+ 0:00.01 script 25623 p1 Ss 0:00.01 /usr/local/bin/bash -i 25624 p1 R+ 0:00.00 ps $ exit Script done, output file is typescript Read More

A restricted shell is a Unix shell that has been modified to allow the Unix shell user to do fewer things than a normal shell would allow him to do. It may allow the user to run only certain programs. It may stop the user from changing directories. Many sites run their own restricted shells to allow limited use of their systems over the Internet. Restricted shells often make use of the restricted shell (rsh). On poorly implemented restricted shells, the shell user can break out of the restricted environment Read More

Securing Linux Installation Installing Linux for securing your server depends upon how to install Linux on desktop or server. Installing Linux from untrusted source would not help in potentially securing your server and overcome on other security issues. You should install those packages only which you are in need because there is always a chance that someone could break into your server if security tasks would not be accomplished during installation and troubleshooting them. Verify Packages and Files on Linux CDs Sources of installation packages should be reliable and safer Read More

A Unix shell is the program which reads user input from the command line and executes actions based upon that input. There are two general families of Unix shells, the Bourne family and the C family. The Bourne shell was the original Unix shell. The C shell was the first competing Unix shell. tcsh is an improved variant of the C shell. The Korn Shell (ksh) and the Bourne Again Shell (bash) are improved variants of the Bourne shell. Other less popular shells include the zsh, rc, and es shells. Read More

Linux is a free, open source operating system that competes with the Windows Operating Systems and Mac OS X. Linux is widely used on a number of devices such as servers, desktops, laptops, smartphones, PDAs, game consoles, tablet computers, supercomputers, and mainframes. Linux controls only about 4.9% of the market share of desktop computers while controlling roughly 40% of the market share of servers. Linux was created and remains to be modified on a routine basis by the community at large as well as specific designers who have been working Read More

Configuring a PPP Server Linux Operating System could be used as PPP Server for configuring both dedicated and dial up connections. For dedicated connections, you should configure pppd and pppd command is used for this. rc.local file is the startup file which is needed to be edited to configure PPP server for dedicated connection. Here you will find how to setup pppoe server on your Linux server. PPP application is installed on Linux server pppd /dev/ttyS1 115700 crtscts PPP daemon will be started with this command and will attach it Read More

For hardcore gamers, the Microsoft Xbox is one of the top consoles ever created. The hardware itself is on par with many desktop computers of just a few years ago, which gave many hackers the great idea of actually making their Xbox into a computer fully equipped with a DVD ROM drive, keyboard, mouse, and monitor (in this case a TV screen). Any Xbox owner who has always wanted to own a Linux computer can now create one with his/her Xbox. Here are some tips. The Xbox is a real Read More

Keeping track of your CPU’s performance is extremely important. In UNIX, you can accomplish this task by using the system utilities and commands. For those who would like to find out their CPU utilization, one command is extremely important. It is called SAR – System Activity Reporter. The SAR commands make accessing CPU performance quite easy. Some simple commands to retrieve CPU utilization include: sar -u The above command will display the current CPU usage. # sar The above command will display the entire day’s CPU usage. # sar -u Read More