Every program which allows a user to log in (telnet, rlogin, pandora,
  etc.) can specify PATH. Shells may as well if it isn't already set.
  There are many slightly different default values, and relying on them
  is a good way to get confused. The only reliable method is to set
  PATH in your shell's startup files. These are different for each
  shell, and are described in each shell's manpage. Beware of 'ksh',
  which has an internal, invisible default path ('/bin:/usr/bin') which
  it uses when PATH is not set.