[Windows/Linux] PHP “exec” missing environment variable causing command not to run

In a recent project, I am finding way to display current git branch on the backend dashboard.
Without a application dependent library, executing CLI git seems to be the fastest way.
i.e. The exactly same syntax as we use in bash/cmd/powershell.

$currentBranch = exec('git rev-parse --abbrev-ref HEAD');

However, it worked in production/staging Linux machine, but not in local Windows machine.
It does work if I specify the absolute path C:\Program Files\Git\bin\git.exe, but it’s not optimal because it will be machine dependent.

After a while, I figure out the environment PATH variable is missing in Windows that cause git not being picked up.
The trick is, add this line before exec call to:

putenv('PATH=' . $_SERVER['PATH']);