If you may received an error when you use CURL command on your terminal "sudo: curl: command not found" which means the curl command it installed in your machine either Ubuntu or CentOS operating system.

Ubuntu / Debain:
I've received the error sudo: curl: command not found when use the CURL command to add the apt-key to install the docker engine,



$ sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -



sudo: curl: command not found


Update the system upto date based on the repository,
$ sudo apt-get update

Install the CURL package in your package in your system,
$ sudo apt-get install curl -y

Then, you can verify the CURL packages whether installed in your machine using the command below,


$ dpkg -l | grep curl



ii  curl                                       7.81.0-1ubuntu1.3                       amd64        command line tool for transferring data with URL syntax

ii  libcurl3-gnutls:amd64                      7.81.0-1ubuntu1.3                       amd64        easy-to-use client-side URL transfer library (GnuTLS flavour)

ii  libcurl4:amd64                             7.81.0-1ubuntu1.3                       amd64        easy-to-use client-side URL transfer library (OpenSSL flavour)


Fedora / RHEL / CentOS:

To install CURL package  on RHEL, CentOS and Fedora distros, execute the command with sudo option, if don't have permission run it in your root user,

$ sudo yum update

$ sudo yum install curl -y

Then, you can verify the CURL packages whether installed in your CentOS using the command below,
$ rpm -qa | grep curl