UNIX processes generally take input from standard input (keyboard), write output to standard out (screen) and may write to standard error if there are any error message which need to be displayed. Among the various powerful functions of Linux systems is the ability to redirect both input and output of commands.

The > symbol redirects output of a command. For example, cal command prints the calendar to screen. Using > we can save this calendar into a file.

A parameter is an entity that stores value and is available to a program. There are many system variables available to BASH. They could be retrieved easily by prefixing a $ sign to the variable. Alternately, you can also surround them with curly braces and prefix a $ sign

#!/bin/bash
#: Title       : print parameters
#: Version     : 1.0
#: Description : print parameters
#: Options     : None

printf "%s " "Current Working Directory"
echo $PWD
printf "%s " "Home Directory"
echo ${HOME}
printf "%s" "Command Directories $PATH"

Output of the script

Error: Could not reliably determine the server’s fully qualified domain name, using 127.0.1.1 for ServerName

Solution: 1. Open httpd.conf for editing

sudo vi /etc/apache2/httpd.conf

You might be surprised to see that the file is empty

2. type the following:

   ServerName localhost

3. Save file and restart apache server

   service apache2 restart

What is the difference between Linux and Linux distribution?

Linux is the core of the operating system i.e. the kernel. Kernel manages the physical resources of the computer and performs tasks such as starting and stopping programs, allocating memory, managing the processor, and managing network connections.

Note: To try out the examples in this document, you would need root access.

To create a new user you use the adduser command. To add a user by called linuxjunky:

$ adduser linuxjunky

If you get a command not found error

$ /usr/sbin/adduser linuxjunky

To assign a password to your new user

$  passwd linuxuser

To grant ownership of a file to the new user

$ chown linuxjunky filename

To change grant ownership of a directory to the new user