Tutorials

1.0 grep

grep is a program for searching a given string pattern in files. It searches the files for the pattern and prints the lines that contain strings matching the pattern. For example,

$ # grep pattern filenames ... 
$ grep 'hbox' find.c
GtkWidget *window, ...

1.0 Shell Script

bash is the commonly used shell in GNU-Linux. bash can be run interactively, as a login shell or as an interactive process from a terminal emulator like the gnome-terminal. bash can be run non-interactively by running a

1.0 SHELL

A shell provides a user interface to a computer system. There are two types of shells, the command line interface (CLI) and the graphical user interface (GUI). In this tutorial, we describe the command line interface shell only and refer to it simply as shell.

A CLI shell is ...

1.0 Network Traffic Control

Computer network traffic is the data moving across the network at a given time. Network bandwidth is the maximum amount of data that can be transmitted over the network in unit time. Computer networks face the possibility of network congestion, where excessive data is trying to pass through the network and there ...

1. ss command

The ss command gives the socket statistics. It gives information about the network connections. ss is a replacement for the netstat command.

By default, the ss command gives information about non-listening sockets.

$ ss
Netid  State ...

File Permissions

In Linux, each files has nine permission bits. There are three basic permissions, read (r), write (w) and execute (x), for a file. These three permissions are there for the owner (o) of the file, the group (g) set for the file and the “others” (o). The ls -l command displays ...

1.0 INTRODUCTION

The iproute2 package contains utilities for network and traffic control. The major commands in iproute2 package are the ip command for IPV4 and IPV6 configuration and tc for traffic control. These commands replace the older ifconfig and the

htop is a ncurses based program for viewing processes in a Linux system. htop gives visual indications about processor, memory and swap usage.

vimdiff works on two, three or four files, opens each file in a separate window and highlights the differences between the files. The files can be edited using the vim commands. vimdiff is a useful tool for finding the differences between different ...

Git is a software source code management (SCM) system, originally developed by Linus Torvalds in 2005 for management of Linux kernel source code. Using Git greatly simplifies the source code management functions for a project and improves the overall efficiency of the software development process. Git ...

1.0 iptables

The iptables command is for defining rules for packet filtering for establishing and configuring firewalls in Linux. iptables, also, helps in configuring the Network Address Translation (NAT) for placing a local area network behind a single public IP address for accessing the Internet and for other uses.

The ...

As we work on different computers at different times, it becomes increasingly difficult to keep track of file versions. For example, you might be working on a development of a new software product on a desktop computer. You might also have the development environment on a laptop and do some work on it occasionally. At ...

1. netstat command

The netstat command in Linux provides network statistics and information about the networking subsystem. It gives information about network connections, routing tables and network interface statistics. For example,

$ netstat
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address          ...

In Internet, the Internet Protocol (IP) is at the Network Layer, which is the third layer of the ISO reference model of network architecture. IP deals with IP packets or datagrams, which are the basic transfer units in the Internet. The higher level protocols like UDP and TCP are built on top of IP datagrams. ...

Linux daemons write log files. Left to itself, these log files would grow with time and take up the disk space. It is necessary to purge the log files periodically so that the disk space is conserved and is available for smooth running of the system. logrotate is a utility for rotation, ...