Assuming you have mySQL or MariaDB installed on a Linux system, the which command can be used to determine if the perror command line tool is installed. In this example, the perror command line tool is installed.

~]# which perror
/bin/perror

The perror command followed by a legitimate error code will display a one liner for the error. For example, to know what error code 110 means.

~]# perror 110
OS error code 110:  Connection timed out