python 正则表达式

以下内容来自python的help(re)指令

re 是python中用于处理正则表达式的库，而help()是python自带的帮助函数，关于python中正则表达式的用法，help()中介绍得十分详细

该文本打印用python中的subprocess库创建执行Shell命令的子进程，在子进程中执行另一个python脚本运行help()函数，并把子进程的stdout和stderr重定向到subprocess的PIPE中，通过子程序的communicate函数来得到stdout和stderr，继而存入文件即可

关于communicate函数
communicate(self, input=None)

 |      Interact with process: Send data to stdin.  Read data from |      stdout and stderr, until end-of-file is reached.  Wait for |      process to terminate.  The optional input argument should be a |      string to be sent to the child process, or None, if no data |      should be sent to the child. |       |      communicate() returns a tuple (stdout, stderr). |   |  kill = terminate(self)

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该说明包含正则表达式的特殊符号、re中的正则表达式的处理方法以及其方法原型和使用说明，十分清晰

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原文如下：

Help on module re:

NAME

re - Support for regular expressions (RE).

FILE

d:\python27\lib\re.py

DESCRIPTION

This module provides regular expression matching operations similar tothose found in Perl.  It supports both 8-bit and Unicode strings; boththe pattern and the strings being processed can contain null bytes andcharacters outside the US ASCII range.Regular expressions can contain both special and ordinary characters.Most ordinary characters, like "A", "a", or "0", are the simplestregular expressions; they simply match themselves.  You canconcatenate ordinary characters, so last matches the string 'last'.The special characters are:    "."      Matches any character except a newline.    "^"      Matches the start of the string.    "$"      Matches the end of the string or just before the newline at             the end of the string.    "*"      Matches 0 or more (greedy) repetitions of the preceding RE.             Greedy means that it will match as many repetitions as possible.    "+"      Matches 1 or more (greedy) repetitions of the preceding RE.    "?"      Matches 0 or 1 (greedy) of the preceding RE.    *?,+?,?? Non-greedy versions of the previous three special characters.    {m,n}    Matches from m to n repetitions of the preceding RE.    {m,n}?   Non-greedy version of the above.    "\\"     Either escapes special characters or signals a special sequence.    []       Indicates a set of characters.             A "^" as the first character indicates a complementing set.    "|"      A|B, creates an RE that will match either A or B.    (...)    Matches the RE inside the parentheses.             The contents can be retrieved or matched later in the string.    (?iLmsux) Set the I, L, M, S, U, or X flag for the RE (see below).    (?:...)  Non-grouping version of regular parentheses.    (?P<name>...) The substring matched by the group is accessible by name.    (?P=name)     Matches the text matched earlier by the group named name.    (?#...)  A comment; ignored.    (?=...)  Matches if ... matches next, but doesn't consume the string.    (?!...)  Matches if ... doesn't match next.    (?<=...) Matches if preceded by ... (must be fixed length).    (?<!...) Matches if not preceded by ... (must be fixed length).    (?(id/name)yes|no) Matches yes pattern if the group with id/name matched,                       the (optional) no pattern otherwise.The special sequences consist of "\\" and a character from the listbelow.  If the ordinary character is not on the list, then theresulting RE will match the second character.    \number  Matches the contents of the group of the same number.    \A       Matches only at the start of the string.    \Z       Matches only at the end of the string.    \b       Matches the empty string, but only at the start or end of a word.    \B       Matches the empty string, but not at the start or end of a word.    \d       Matches any decimal digit; equivalent to the set [0-9].    \D       Matches any non-digit character; equivalent to the set [^0-9].    \s       Matches any whitespace character; equivalent to [ \t\n\r\f\v].    \S       Matches any non-whitespace character; equiv. to [^ \t\n\r\f\v].    \w       Matches any alphanumeric character; equivalent to [a-zA-Z0-9_].             With LOCALE, it will match the set [0-9_] plus characters defined             as letters for the current locale.    \W       Matches the complement of \w.    \\       Matches a literal backslash.This module exports the following functions:    match    Match a regular expression pattern to the beginning of a string.    search   Search a string for the presence of a pattern.    sub      Substitute occurrences of a pattern found in a string.    subn     Same as sub, but also return the number of substitutions made.    split    Split a string by the occurrences of a pattern.    findall  Find all occurrences of a pattern in a string.    finditer Return an iterator yielding a match object for each match.    compile  Compile a pattern into a RegexObject.    purge    Clear the regular expression cache.    escape   Backslash all non-alphanumerics in a string.Some of the functions in this module takes flags as optional parameters:    I  IGNORECASE  Perform case-insensitive matching.    L  LOCALE      Make \w, \W, \b, \B, dependent on the current locale.    M  MULTILINE   "^" matches the beginning of lines (after a newline)                   as well as the string.                   "$" matches the end of lines (before a newline) as well                   as the end of the string.    S  DOTALL      "." matches any character at all, including the newline.    X  VERBOSE     Ignore whitespace and comments for nicer looking RE's.    U  UNICODE     Make \w, \W, \b, \B, dependent on the Unicode locale.This module also defines an exception 'error'.

CLASSES

exceptions.Exception(exceptions.BaseException)    sre_constants.errorclass error(exceptions.Exception) |  Method resolution order: |      error |      exceptions.Exception |      exceptions.BaseException |      __builtin__.object |   |  Data descriptors defined here: |   |  __weakref__ |      list of weak references to the object (if defined) |   |  ---------------------------------------------------------------------- |  Methods inherited from exceptions.Exception: |   |  __init__(...) |      x.__init__(...) initializes x; see help(type(x)) for signature |   |  ---------------------------------------------------------------------- |  Data and other attributes inherited from exceptions.Exception: |   |  __new__ = <built-in method __new__ of type object> |      T.__new__(S, ...) -> a new object with type S, a subtype of T |   |  ---------------------------------------------------------------------- |  Methods inherited from exceptions.BaseException: |   |  __delattr__(...) |      x.__delattr__('name') <==> del x.name |   |  __getattribute__(...) |      x.__getattribute__('name') <==> x.name |   |  __getitem__(...) |      x.__getitem__(y) <==> x[y] |   |  __getslice__(...) |      x.__getslice__(i, j) <==> x[i:j] |       |      Use of negative indices is not supported. |   |  __reduce__(...) |   |  __repr__(...) |      x.__repr__() <==> repr(x) |   |  __setattr__(...) |      x.__setattr__('name', value) <==> x.name = value |   |  __setstate__(...) |   |  __str__(...) |      x.__str__() <==> str(x) |   |  __unicode__(...) |   |  ---------------------------------------------------------------------- |  Data descriptors inherited from exceptions.BaseException: |   |  __dict__ |   |  args |   |  message

FUNCTIONS

compile(pattern, flags=0)    Compile a regular expression pattern, returning a pattern object.escape(pattern)    Escape all non-alphanumeric characters in pattern.findall(pattern, string, flags=0)    Return a list of all non-overlapping matches in the string.    If one or more groups are present in the pattern, return a    list of groups; this will be a list of tuples if the pattern    has more than one group.    Empty matches are included in the result.finditer(pattern, string, flags=0)    Return an iterator over all non-overlapping matches in the    string.  For each match, the iterator returns a match object.    Empty matches are included in the result.match(pattern, string, flags=0)    Try to apply the pattern at the start of the string, returning    a match object, or None if no match was found.purge()    Clear the regular expression cachesearch(pattern, string, flags=0)    Scan through string looking for a match to the pattern, returning    a match object, or None if no match was found.split(pattern, string, maxsplit=0, flags=0)    Split the source string by the occurrences of the pattern,    returning a list containing the resulting substrings.sub(pattern, repl, string, count=0, flags=0)    Return the string obtained by replacing the leftmost    non-overlapping occurrences of the pattern in string by the    replacement repl.  repl can be either a string or a callable;    if a string, backslash escapes in it are processed.  If it is    a callable, it's passed the match object and must return    a replacement string to be used.subn(pattern, repl, string, count=0, flags=0)    Return a 2-tuple containing (new_string, number).    new_string is the string obtained by replacing the leftmost    non-overlapping occurrences of the pattern in the source    string by the replacement repl.  number is the number of    substitutions that were made. repl can be either a string or a    callable; if a string, backslash escapes in it are processed.    If it is a callable, it's passed the match object and must    return a replacement string to be used.template(pattern, flags=0)    Compile a template pattern, returning a pattern object

DATA

DOTALL = 16I = 2IGNORECASE = 2L = 4LOCALE = 4M = 8MULTILINE = 8S = 16U = 32UNICODE = 32VERBOSE = 64X = 64__all__ = ['match', 'search', 'sub', 'subn', 'split', 'findall', 'comp...__version__ = '2.2.1'

VERSION

2.2.1