Since Magento 184.108.40.206 the SSH upgrade command has been changed to ./mage instead of ./pear. If you have used ./pear upgrade-all in the past, you will now have to use the ./mage version. I was upgrading from Magento 220.127.116.11 to Magento 18.104.22.168. I’m using the Community Edition.
For ./mage to work you need to CHMOD it to have sufficient permissions. Then you need to add the newer 1.5 version of Magento pear channels. The following worked for me on the Magento 22.214.171.124 install. As always please do not try this on a production site. Create a staging version of your Magento store before you try upgrading. Also, remember to backup your database. One more thing: please remember to point local.xml to the new database and not the production one. :)
./mage channel-add connect20.magentocommerce.com/community ./mage channel-add connect20.magentocommerce.com/core ./mage sync ./mage upgrade-all --force