Use defaults to edit preferences
Your command is adding a BOOL true or false.

So you needed to declare it as such by adding -bool. Otherwise you are changing to a string.

But also with this change you need to relaunch the dock for it to pick up the changes. You can do this by adding a second command.

killAll Dock


In one command:

defaults write com.apple.dock autohide  -bool no;killAll Dock 


This will run your command and kill any process named Dock. The Dock will then auto relaunch picking up the changes.