cd [−L|−P] [directory]

    cd [−L] [directory]
    cd −P [−e] [directory]

    If both the −e and the −P options are in effect and cd is unable to determine the
    pathname of the current working directory, cd shall complete successfully but
    return a non-zero exit status.

    −e      If the −P option is in effect, the current working directory is successfully
            changed, and the correct value of the PWD environment variable cannot be
            determined, exit with exit status 1.

     0      The directory was successfully changed.
    >0      An error occurred.

     0      The current working directory was successfully changed and the value of
            the PWD environment variable was set correctly.
     0      The current working directory was successfully changed, the −e option is
            not in effect, the −P option is in effect, and the correct value of the PWD
            environment variable could not be determined.
    >0      Either the −e option or the −P option is not in effect, and an error occurred.
     1      The current working directory was successfully changed, both the −e and
            the −P options are in effect, and the correct value of the PWD environment
            variable could not be determined.
    >1      Both the −e and the −P options are in effect, and an error occurred.

    When the −P option is in effect, the correct value of the PWD environment
    variable cannot be determined on some systems, but still results in a zero
    exit status.  The value of the $PWD doesn't matter to some shell scripts
    and in those cases this is not a problem.  In other cases, especially with
    multiple calls to cd, the values of $PWD and $OLDPWD are important but
    the standard provided no easy way to know that this was the case.  The
    −e option has been added, even though this was not historic practice, to
    give script writers a reliable way to know when the value of $PWD is not
    reliable.