Getting Error to install drush

[abdulz_khan]

When i run 'pear channel-discover pear.drush.org' command to install drush then facing below issue:

Trying to discover channel pear.drush.org over https:// instead Discovery of channel "pear.drush.org" failed (channel-add: Cannot open "https://pear.drush.org/channel.xml" (Connection to `pear.drush.org:443' failed: php_network_getaddresses: getaddrinfo failed: Name or service not known)