Networking Commands Miscellaneous Commands

Network Connectivity

ping

checks the network connectivity between host and server/host.

Syntax :

1

ping hostname/IP address

Example :

1

ping google.com

Route Path

traceroute

prints the route that a packet takes to reach the host.

Syntax :

1

traceroute host_address

Example :

1

traceroute google.com

Network Interface

A network interface is a software interface to networking hardware.

Different types of network interfaces are:

• Ethernet

• Loopback etc.

Information About Network Interfaces

ifconfig

ifconfig

gives you the information of various network interfaces.

1

ifconfig

Ethernet Interface

exxxx is a physical interface representing Ethernet network card.

Loopback Interface

• lo is a special virtual network interface called loopback device.

• It is used to connect to services running on the user system

  

Environment Setup

Environment Variables

• Linux environment variables act as placeholders for information stored within the system.

• They will be available to the programs launched from the shell.

Listing

env

command can be used to print all the environment variables.

1

env

Creating & Updating

export

command is used to define/update value for a variable.

Syntax :

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export VARIABLE_NAME=variable_value

Example :

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export CUSTOM_ENV_VARIABLE=10

Accessing Environment Variables

• Use $ to access environment variables.

• When redefining variables, do not use the dollar sign.

Syntax :

1

echo $VARIABLE_NAME

Example :

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$ echo $CUSTOM_ENV_VARIABLE

Delete Environment Variable

unset

command removes an environment variable.

1

unset VARIABLE_NAME

Commands Folder Path

PATH variable holds the colon-separated list of folder paths where executables are located.

1

echo $PATH

Aliasing Command

alias

is a (usually short) name that the shell translates into another name or command.

Syntax :

1

alias name=value

Example :

1

2

alias t=traceroute

t google.com

Un-aliasing Command

unalias

removing an existing alias is known as unaliasing.

1

unalias alias_name

Persistent Variables

Environment variables defined in a shell are deleted as soon as you exit the terminal.

To persistent environment variables we write them in .bashrc or ~/.bash_profile configuration files.

Editing .bashrc

Syntax :

1

export VARIABLE_NAME=variable_value

Example :

1

2

3

4

5

6

7

# ~/.bashrc: executed by bash(1) for non-login shells.

# see /usr/share/doc/bash/Examples/startup-files (in the package bash-doc)

# for Examples

case $- in

*i*) ;

...

export CUSTOM_ENV_VARIABLE=5

• To immediately apply all changes in .bashrc,
  use the 
  source
   command

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source ~/.bashrc

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