cd —
change working directory
Since cd affects the current shell execution
  environment, it is always provided as a shell regular built-in. For more
  information consult the manual page for the shell in use.
The directory operand is an absolute or
    relative pathname which becomes the new working directory. The
    interpretation of a relative pathname by cd depends
    on the CDPATH environment variable (see below).
The following environment variables affect the execution of
  cd:
  - CDPATH
- A colon-separated list of pathnames that refer to directories. If the
      directory operand does not begin with a slash
      (‘/’) character, and the first
      component is not dot (‘.’) or
      dot-dot (‘..’),cdsearches for the
      directory relative to each directory named in theCDPATHvariable, in the order listed. The new
      working directory is set to the first matching directory found. An empty
      string in place of a directory pathname represents the current directory.
      If the new working directory was derived fromCDPATH, it will be printed to the standard
    output.
- HOME
- If cdis invoked without arguments and theHOMEenvironment variable exists and contains a
      directory name, that directory becomes the new working directory.
- OLDPWD
- Set to the previous working directory after a directory change. Not
      supported by csh(1).
- PWD
- Set to the current working directory.
Thecd utility exits 0 on success,
  and >0 if an error occurs.
The cd command is expected to be IEEE
  Std 1003.2 (“POSIX.2”) compatible.