chkconfig:tldr:816c2

The command "chkconfig --level ${2345} ${sshd} on" is used to enable the service "sshd" to start automatically at runlevels 2, 3, 4, and 5 in a Unix-like operating system.

Here's a breakdown of the command:

• "chkconfig" is a command-line utility that allows you to configure services on a Unix-like system.
• "--level ${2345}" specifies the runlevels at which the service should be enabled. Runlevels 2, 3, 4, and 5 are commonly used for multi-user mode in most Unix-like systems.
• "${sshd}" is a variable representing the name of the service. In this case, "sshd" refers to the SSH (Secure Shell) daemon, which is responsible for remote administration and secure communication on a server.
• "on" is an option that enables the service at the specified runlevels.

So, the command instructs the system to enable the SSH daemon to start automatically at the specified runlevels, allowing remote access via SSH to the system for administrative purposes.