> What happens if someone's creating a script that will shell out simultaneously to multiple Go programs? Do they all inherit the parent's environment variables?
By default, every process inherits the environment of its parent process. So if you set an environment variable (eg. with the EXPORT command in bash), then every process you launch from the shell will have the same value for the environment variable.
However, you can set environment variables for each command that you execute.
So for example in a shell script you could do something like this:
# set the environment variables value to 4
# valid for all subsequently executed commands
export GOMAXPROCS=4
# run syncthing but limit it to 2 processors
# defining the variable like this it will only affect this command
GOMAXPROCS=2 /usr/local/bin/syncthing
# run some other go program
# the environment var will be set to the value 4 again
/usr/local/bin/other-go-program
The beauty of using environment variables is that they are much more flexible than command line options.
For example, assume I execute a script from someone else, who did not set GOMAXPROCS. Then I could just set the GOMAXPROCS variable and then execute the script. I could change the config without needing to edit the script!