source command on available on all Linuxes

[miohtama]

There is a gotcha with shell source command with virtualenv. source is not standard and not available on all Linuxes (or more accurately on their default shells). Instead one should use more common .. If you do source then some people might simply get Command not found when they try to follow the installation instructions.

Namely the late Ubuntus and its dash shell might be problematic. The issue is discussed here: https://wiki.ubuntu.com/DashAsBinSh#source

[oinopion]

Due to the . being used to mean current directory in other contexts I've decided to not recommend it as default. There's a note [640bf06] to help troubleshoot problems with source on dash et al.