How to find the file size of a remote HTTP object?

There are times when you need to know the file size of an HTTP object without actually downloading the file. This little trick comes in very handy when web servers respond with the Content-Length of an object in the HEAD request itself.

Using curl command:

Example:

curl -sI https://releases.ubuntu.com/20.04.2.0/ubuntu-20.04.2.0-desktop-amd64.iso | grep Content-Length

Content-Length: 2877227008

Let’s try and make this human-friendly:

curl -sI https://releases.ubuntu.com/20.04.2.0/ubuntu-20.04.2.0-desktop-amd64.iso | grep Content-Length | sed 's/[^0-9]//g' | numfmt --to=si

2.9G

Where The Numfmt command will convert the numbers to/from human-readable format.

how to find my public ip address in linux ?

Using dig

dig (domain information groper) is a simple command line utility for probing DNS name servers. To find your public IP addresses, use the opendns.com resolver as in the command below:

Syntax:

dig +short myip.opendns.com @resolver1.opendns.com

Example:

dig +short myip.opendns.com @resolver1.opendns.com

111.125.200.200

Using host

host command is an easy-to-use command line utility for carrying out DNS lookups. The command below will help to display your system public IP address.

Syntax:

host myip.opendns.com resolver1.opendns.com | grep "myip.opendns.com has" | awk '{print $4}'

Example:

host myip.opendns.com resolver1.opendns.com | grep "myip.opendns.com has" | awk '{print $4}'

111.125.200.200

Using wget

curl is a popular command line tool for uploading or downloading files from a server using any of the supported protocols (HTTP, HTTPS, FILE, FTP, FTPS and others). The following

commands display your public IP address.

Syntax:

wget -qO- http://ipecho.net/plain | xargs echo

Or

wget -qO - icanhazip.com

Example:

 wget -qO- http://ipecho.net/plain | xargs echo

111.125.200.200

 wget -qO- http://ipecho.net/plain | xargs echo

111.125.200.200

Using curl

curl is a popular command line tool for uploading or downloading files from a server using any of the supported protocols (HTTP, HTTPS, FILE, FTP, FTPS and others). The following

commands display your public IP address.

Syntax:

curl ifconfig.me

Example:

curl ifconfig.me

111.125.200.200

The following commands will get you the IP address list to find public IP addresses for your machine:

• curl ifconfig.me
• curl icanhazip.com
• curl ipinfo.io/ip
• curl api.ipify.org
• curl checkip.dyndns.org
• curl ident.me
• curl bot.whatismyipaddress.com
• curl ipecho.net/plain