What is the easiest way to check if Nginx is installed on the server?

# Check for the presence of the Nginx executable in PATH
which nginx

# Check the status of the Nginx service (for systemd systems)
systemctl status nginx

# Check the status of the Nginx service (for SysVinit/Upstart systems)
service nginx status

# Get the current version of Nginx (if installed)
ginx -v

The simplest way is to use a command that attempts to execute the Nginx executable or check the status of its service. If the command executes successfully, it indicates that Nginx is present. The command output may also provide information about the status or version, further confirming the installation. Using which checks for the executable in the paths defined in the PATH environment variable. Using systemctl or service checks the registered system service, which is more reliable for verifying an active and configured instance.