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Accessing Network from shell

This document explains how Unix based OS can access and communicate with LAN and Internet. Lets get started.

1. curl - Get a webpage

# Syntax
curl [options] [URL...]

Examples: 

Fetch the file index.htm from www.computerhope.com over HTTP, and display it to stdout
curl https://www.computerhope.com/index.htm

Fetch and save to file myindex.htm
curl https://www.computerhope.com/index.htm > myindex.htm

# Fetch and output to a file with the same name (index.htm),  curl OPTION -O
curl -O https://www.computerhope.com/index.htm

Try yourself 

curl https://towshif.com

wget [OPTIONS] [URL LINK TO FILE]

Try yourself 

wget https://www.livingandloving.co.za/wp-content/uploads/2017/02/How-to-cope-with-your-babys-acid-reflux.jpg

This command will download the following baby image to your local machine baby

OPTION -c: 

# if a partial download exists, resume the download where it left off.
wget -c http://www.example.org/files/archive.zip

OPTION -b

# Download in the background, returning you to the command prompt in the interim.
wget -b http://www.example.org/files/archive.zip
# in above case wget-log appears in the specified download directory 
tail -f wget-log

wget Over FTP with auth

wget --ftp-user=YOUR_USERNAME --ftp-password=YOUR_PASSWORD ftp://example.com/something.tar

3. ssh - secure shell access

ssh [OPTIONS] [user]@[host]

Examples: 

# Basic usage     
ssh [USERNAME]@[IP_ADDRESS or HOSTNAME]

# with custom PORT; default PORT:22
ssh -p [PORT] [USERNAME]@[IP_ADDRESS or HOSTNAME]

4. scp - Copy a file across network servers

scp [OPTIONS] [USER]@[SOURCE_HOST]:[SOURCE FILEPATH] [USER]@[DESTINATION_HOST]:[DEST FILEPATH]

Example: scp file copy from one host to another / local machine. 

# Copy file from a remote host to local host SCP example:
scp username@from_host:file.txt /local/directory/

# Copy file from local host to a remote host SCP example:
scp file.txt username@to_host:/remote/directory/

# Copy directory from a remote host to local host SCP example:
scp -r username@from_host:/remote/directory/  /local/directory/

# Copy directory from local host to a remote hos SCP example:
scp -r /local/directory/ username@to_host:/remote/directory/

# Copy file from remote host to remote host SCP example:
scp username@from_host:/remote/directory/file.txt username@to_host:/remote/directory/

With Custom PORT -P option example scp port 90: 

 scp -P 90 username@from_host:/remote/directory/file.txt username@to_host:/remote/directory/

In case both ports are different then use 2 steps via a local directory to copy from HOST1 to HOST2