How do I install curl on my server?

There are two types of curl programs that we can install. One is the curl program for the command line and the other is a module for php.

Installing Command Line curl
To install the command line curl for Ubuntu/Debian, run the apt-get install curl command. Proceed to verify the installation by running curl -V.
For other distributions, you can refer to this guide by TecMint.com.

Installing php-curl
To install php-curl on your Linode running Ubuntu/Debian,

1. First, update your ubuntu system first.
   apt-get update

2. Check the version of php.
   php -v

3. Install php-curl
   apt-get install php-curl
   (Add the version number after "php" to install the correct version. Example: To install version 5.6, you will run apt-get install php5.6-curl)

4. Verify curl is installed and check its version.
   dpkg -l *curl*

You can find more on installing php-curl for other distributions here.