launch a xcodeproj from terminal

If you want to run an app from the command line, use

open /path/to/appname.app

"Build and Go" is really just equivalent to

xcodebuild [parameters] && open /path/to/appname.app

To run an Xcode project from terminal:

open *.xcodeproj

It may also be helpful to create an alias:

alias xcode="open *.xcodeproj"

Are you asking for the command to build from the command-line?

It's just:

xcodebuild

There are lots of options available to pick non-default options:

Usage: xcodebuild [-project <projectname>] [-activetarget] [-alltargets] [-target <targetname>]... [-parallelizeTargets] [-activeconfiguration] [-configuration <configurationname>] [-sdk <sdkfullpath>|<sdkname>] [<buildsetting>=<value>]... [<buildaction>]...
   xcodebuild [-version [-sdk <sdkfullpath>|<sdkname>]]
   xcodebuild [-showsdks]
   xcodebuild [-find <binary>] [-sdk <sdkfullpath>|<sdkname>]
   xcodebuild [-list]