--登录python
[root@bakdbserver ~]# python
Python 2.7.5 (default, Aug  7 2013, 21:50:17)
[GCC 4.1.2 20080704 (Red Hat 4.1.2-54)] on linux2
Type "help", "copyright", "credits" or "license" for more information.

 

--进入帮助模式状态
>>> help()

Welcome to Python 2.7!  This is the online help utility.

If this is your first time using Python, you should definitely check out
the tutorial on the Internet at http://docs.python.org/2.7/tutorial/.

Enter the name of any module, keyword, or topic to get help on writing
Python programs and using Python modules.  To quit this help utility and
return to the interpreter, just type "quit".

To get a list of available modules, keywords, or topics, type "modules",
"keywords", or "topics".  Each module also comes with a one-line summary
of what it does; to list the modules whose summaries contain a given word
such as "spam", type "modules spam".

 

--组件列表
help> modules

Please wait a moment while I gather a list of all available modules...

BaseHTTPServer      array               imghdr              sha
Bastion             ast                 imp                 shelve
CDROM               asynchat            importlib           shlex
CGIHTTPServer       asyncore            imputil             shutil
Canvas              atexit              inspect             signal
ConfigParser        audiodev            io                  site
Cookie              audioop             itertools           smtpd
DLFCN               base64              json                smtplib
Dialog              bdb                 keyword             sndhdr
DocXMLRPCServer     binascii            lib2to3             socket
FileDialog          binhex              linecache           spwd
FixTk               bisect              linuxaudiodev       sqlite3
HTMLParser          bsddb               locale              sre
IN                  cPickle             logging             sre_compile
MimeWriter          cProfile            macpath             sre_constants
Queue               cStringIO           macurl2path         sre_parse
ScrolledText        calendar            mailbox             ssl
SimpleDialog        cgi                 mailcap             stat
SimpleHTTPServer    cgitb               markupbase          statvfs
SimpleXMLRPCServer  chunk               marshal             string
SocketServer        cmath               math                stringold
StringIO            cmd                 md5                 stringprep
TYPES               code                mhlib               strop
Tix                 codecs              mimetools           struct
Tkconstants         codeop              mimetypes           subprocess
Tkdnd               collections         mimify              sunau
Tkinter             colorsys            mmap                sunaudio
UserDict            commands            modulefinder        symbol
UserList            compileall          multifile           symtable
UserString          compiler            multiprocessing     sys
_LWPCookieJar       contextlib          mutex               sysconfig
_MozillaCookieJar   cookielib           netrc               syslog
__builtin__         copy                new                 tabnanny
__future__          copy_reg            nis                 tarfile
_abcoll             crypt               nntplib             telnetlib
_ast                csv                 ntpath              tempfile
_bisect             ctypes              nturl2path          termios
_codecs             curses              numbers             test
_codecs_cn          datetime            opcode              textwrap
_codecs_hk          dbhash              operator            this
_codecs_iso2022     decimal             optparse            thread
_codecs_jp          difflib             os                  threading
_codecs_kr          dircache            os2emxpath          time
_codecs_tw          dis                 ossaudiodev         timeit
_collections        distutils           parser              tkColorChooser
_csv                doctest             pdb                 tkCommonDialog
_ctypes             dumbdbm             pickle              tkFileDialog
_ctypes_test        dummy_thread        pickletools         tkFont
_elementtree        dummy_threading     pipes               tkMessageBox
_functools          email               pkgutil             tkSimpleDialog
_heapq              encodings           platform            toaiff
_hotshot            errno               plistlib            token
_io                 exceptions          popen2              tokenize
_json               fcntl               poplib              trace
_locale             filecmp             posix               traceback
_lsprof             fileinput           posixfile           ttk
_md5                fnmatch             posixpath           tty
_multibytecodec     formatter           pprint              turtle
_multiprocessing    fpformat            profile             types
_osx_support        fractions           pstats              unicodedata
_pyio               ftplib              pty                 unittest
_random             functools           pwd                 urllib
_sha                future_builtins     py_compile          urllib2
_sha256             gc                  pyclbr              urlparse
_sha512             genericpath         pydoc               user
_socket             getopt              pydoc_data          uu
_sre                getpass             pyexpat             uuid
_strptime           gettext             quopri              warnings
_struct             glob                random              wave
_symtable           grp                 re                  weakref
_sysconfigdata      gzip                repr                webbrowser
_testcapi           hashlib             resource            whichdb
_threading_local    heapq               rexec               wsgiref
_warnings           hmac                rfc822              xdrlib
_weakref            hotshot             rlcompleter         xml
_weakrefset         htmlentitydefs      robotparser         xmllib
abc                 htmllib             runpy               xmlrpclib
aifc                httplib             sched               xxsubtype
antigravity         idlelib             select              zipfile
anydbm              ihooks              sets                zipimport
argparse            imaplib             sgmllib            

Enter any module name to get more help.  Or, type "modules spam" to search
for modules whose descriptions contain the word "spam".

 

--具体组件的使用
help> modules sets

Here is a list of matching modules.  Enter any module name to get more help.

sets - Classes to represent arbitrary sets (including sets of sets).
test.test_sets

help> modules random

Here is a list of matching modules.  Enter any module name to get more help.

ctypes.test.test_random_things
random - Random variable generators.
test.test_random
_random

--列出所有关键字
help> keywords

Here is a list of the Python keywords.  Enter any keyword to get more help.

and                 elif                if                  print
as                  else                import              raise
assert              except              in                  return
break               exec                is                  try
class               finally             lambda              while
continue            for                 not                 with
def                 from                or                  yield
del                 global              pass               

--具体关键字的使用
help> if
The ``if`` statement
********************

The ``if`` statement is used for conditional execution:

   if_stmt ::= "if" expression ":" suite
               ( "elif" expression ":" suite )*
               ["else" ":" suite]

 

--列出所有topics
help> topics

Here is a list of available topics.  Enter any topic name to get more help.

ASSERTION           DEBUGGING           LITERALS            SEQUENCEMETHODS2
ASSIGNMENT          DELETION            LOOPING             SEQUENCES
ATTRIBUTEMETHODS    DICTIONARIES        MAPPINGMETHODS      SHIFTING
ATTRIBUTES          DICTIONARYLITERALS  MAPPINGS            SLICINGS
AUGMENTEDASSIGNMENT DYNAMICFEATURES     METHODS             SPECIALATTRIBUTES
BACKQUOTES          ELLIPSIS            MODULES             SPECIALIDENTIFIERS
BASICMETHODS        EXCEPTIONS          NAMESPACES          SPECIALMETHODS
BINARY              EXECUTION           NONE                STRINGMETHODS
BITWISE             EXPRESSIONS         NUMBERMETHODS       STRINGS
BOOLEAN             FILES               NUMBERS             SUBSCRIPTS
CALLABLEMETHODS     FLOAT               OBJECTS             TRACEBACKS
CALLS               FORMATTING          OPERATORS           TRUTHVALUE
CLASSES             FRAMEOBJECTS        PACKAGES            TUPLELITERALS
CODEOBJECTS         FRAMES              POWER               TUPLES
COERCIONS           FUNCTIONS           PRECEDENCE          TYPEOBJECTS
COMPARISON          IDENTIFIERS         PRINTING            TYPES
COMPLEX             IMPORTING           PRIVATENAMES        UNARY
CONDITIONAL         INTEGER             RETURNING           UNICODE
CONTEXTMANAGERS     LISTLITERALS        SCOPING            
CONVERSIONS         LISTS               SEQUENCEMETHODS1   

--具体topics用法
help> FLOAT
Floating point literals
***********************

Floating point literals are described by the following lexical
definitions:

   floatnumber   ::= pointfloat | exponentfloat
   pointfloat    ::= [intpart] fraction | intpart "."
   exponentfloat ::= (intpart | pointfloat) exponent
   intpart       ::= digit+
   fraction      ::= "." digit+
   exponent      ::= ("e" | "E") ["+" | "-"] digit+

Note that the integer and exponent parts of floating point numbers can
look like octal integers, but are interpreted using radix 10.  For
example, ``077e010`` is legal, and denotes the same number as
``77e10``. The allowed range of floating point literals is
implementation-dependent. Some examples of floating point literals:

   3.14    10.    .001    1e100    3.14e-10    0e0

 

--离开帮助状态模式
help> quit
You are now leaving help and returning to the Python interpreter.
If you want to ask for help on a particular object directly from the
interpreter, you can type "help(object)".  Executing "help('string')"
has the same effect as typing a particular string at the help> prompt.

 

--查看具体对象帮助
>>> a=1
>>> a
1
>>> help(a)
Help on int object:

class int(object)
 |  int(x=0) -> int or long
 |  int(x, base=10) -> int or long
 | 
 |  Convert a number or string to an integer, or return 0 if no arguments
 |  are given.  If x is floating point, the conversion truncates towards zero.
 |  If x is outside the integer range, the function returns a long instead.
 | 
 |  If x is not a number or if base is given, then x must be a string or
 |  Unicode object representing an integer literal in the given base.  The
 |  literal can be preceded by '+' or '-' and be surrounded by whitespace.
 |  The base defaults to 10.  Valid bases are 0 and 2-36.  Base 0 means to
 |  interpret the base from the string as an integer literal.
 |  >>> int('0b100', base=0)
 |  4
 | 
 |  Methods defined here:
 | 
 |  __abs__(...)
 |      x.__abs__() <==> abs(x)
 | 
 |  __add__(...)
 |      x.__add__(y) <==> x+
.......
 |      x.__floordiv__(y) <==> x//y
 | 
 |  __format__(...)
 | 
:   ##输入q离开帮助

--或是直接使用 help(int)效果是一样的