shebang - weakish/cheat GitHub Wiki
In scripting, a shebang line will tell its interpretor.
In most cases, use env, so users may install the interpretor anywhere.
#!/usr/bin/env lang
But occasionally, do not use env, as it may not be present in some systems:
#!/bin/sh
(Well, even busybox has env.
But Android by default does not have env.
Though #!/bin/sh won't work, either, since Android uses #!/system/bin/sh)