Shebang (Unix) (Wikipedia)

Why do people write #!/usr/bin/env python on the first line of a Python script?

Examples:

• #!/usr/bin/env python
• #!/usr/bin/python

Note: The env utility allows you to invoke a command on the PATH. The first argument specifies the program name to invoke; it is searched for according to the PATH environment variable. Any remaining arguments are passed as arguments to that program.