shutil
python为什么叫爬虫、 -- --High-level file operations 高级的文件操作模块。
os模块提供了对目录或者文件的新建/删除/查看文件属性，还提供了对文件以及目录的路径操作。比如说：绝对路径，父目录…… 但是，os文件的操作还应该包含移动 复制 打包 压缩 解压等操作，这些os模块都没有提供。
而本章所讲的shutil则就是对os中文件操作的补充。--移动 复制 打包 压缩 解压，
shutil功能：
1 shutil.copyfileobj(fsrc, fdst[, length=16*1024]) #copy文件内容到另一个文件，可以copy指定大小的内容
#先来看看其源代码。 def copyfileobj(fsrc, fdst, length=16*1024):"""copy data from file-like object fsrc to file-like object fdst"""while 1:buf = fsrc.read(length)if not buf:breakfdst.write(buf)#注意！ 在其中fsrc，fdst都是文件对象，都需要打开后才能进行复制操作 import shutil f1=open('name','r') f2=open('name_copy','w+') shutil.copyfileobj(f1,f2,length=16*1024)
2 shutil.copyfile(src,dst) #copy文件内容，是不是感觉上面的文件复制很麻烦？还需要自己手动用open函数打开文件，在这里就不需要了，事实上，copyfile调用了copyfileobj
def copyfile(src, dst, *, follow_symlinks=True):"""Copy data from src to dst.If follow_symlinks is not set and src is a symbolic link, a newsymlink will be created instead of copying the file it points to."""if _samefile(src, dst):raise SameFileError("{!r} and {!r} are the same file".format(src, dst))for fn in [src, dst]:try:st = os.stat(fn)except OSError:# File most likely does not existpasselse:# XXX What about other special files? (sockets, devices...)if stat.S_ISFIFO(st.st_mode):raise SpecialFileError("`%s` is a named pipe" % fn)if not follow_symlinks and os.path.islink(src):os.symlink(os.readlink(src), dst)else:with open(src, 'rb') as fsrc:with open(dst, 'wb') as fdst:copyfileobj(fsrc, fdst)return dst
shutil.copyfile('name','name_copy_2') #一句就可以实现复制文件内容
3 shutil.copymode(src,dst) #仅copy权限，不更改文件内容，组和用户。
def copymode(src, dst, *, follow_symlinks=True):"""Copy mode bits from src to dst.If follow_symlinks is not set, symlinks aren't followed if and onlyif both `src` and `dst` are symlinks. If `lchmod` isn't available(e.g. Linux) this method does nothing."""if not follow_symlinks and os.path.islink(src) and os.path.islink(dst):if hasattr(os, 'lchmod'):stat_func, chmod_func = os.lstat, os.lchmodelse:returnelif hasattr(os, 'chmod'):stat_func, chmod_func = os.stat, os.chmodelse:returnst = stat_func(src)chmod_func(dst, stat.S_IMODE(st.st_mode))
#先看两个文件的权限 [root@slyoyo python_test]# ls -l total 4 -rw-r--r--. 1 root root 79 May 14 05:17 test1 -rwxr-xr-x. 1 root root 0 May 14 19:10 test2#运行命令 >>> import shutil >>> shutil.copymode('test1','test2')#查看结果 [root@slyoyo python_test]# ls -l total 4 -rw-r--r--. 1 root root 79 May 14 05:17 test1 -rw-r--r--. 1 root root 0 May 14 19:10 test2#当我们将目标文件换为一个不存在的文件时报错 >>> shutil.copymode('test1','test3') Traceback (most recent call last):File "<stdin>", line 1, in <module>File "/usr/local/python/lib/python3.4/shutil.py", line 132, in copymodechmod_func(dst, stat.S_IMODE(st.st_mode)) FileNotFoundError: [Errno 2] No such file or directory: 'test233'
4 shutil.copystat(src,dst) #复制所有的状态信息，包括权限，组，用户，时间等
def copystat(src, dst, *, follow_symlinks=True):"""Copy all stat info (mode bits, atime, mtime, flags) from src to dst.If the optional flag `follow_symlinks` is not set, symlinks aren't followed if andonly if both `src` and `dst` are symlinks."""def _nop(*args, ns=None, follow_symlinks=None):pass# follow symlinks (aka don't not follow symlinks)follow = follow_symlinks or not (os.path.islink(src) and os.path.islink(dst))if follow:# use the real function if it existsdef lookup(name):return getattr(os, name, _nop)else:# use the real function only if it exists# *and* it supports follow_symlinksdef lookup(name):fn = getattr(os, name, _nop)if fn in os.supports_follow_symlinks:return fnreturn _nopst = lookup("stat")(src, follow_symlinks=follow)mode = stat.S_IMODE(st.st_mode)lookup("utime")(dst, ns=(st.st_atime_ns, st.st_mtime_ns),follow_symlinks=follow)try:lookup("chmod")(dst, mode, follow_symlinks=follow)except NotImplementedError:# if we got a NotImplementedError, it's because# * follow_symlinks=False,# * lchown() is unavailable, and# * either# * fchownat() is unavailable or# * fchownat() doesn't implement AT_SYMLINK_NOFOLLOW.# (it returned ENOSUP.)# therefore we're out of options--we simply cannot chown the# symlink. give up, suppress the error.# (which is what shutil always did in this circumstance.)passif hasattr(st, 'st_flags'):try:lookup("chflags")(dst, st.st_flags, follow_symlinks=follow)except OSError as why:for err in 'EOPNOTSUPP', 'ENOTSUP':if hasattr(errno, err) and why.errno == getattr(errno, err):breakelse:raise_copyxattr(src, dst, follow_symlinks=follow)
5 shutil.copy(src,dst) #复制文件的内容以及权限，先copyfile后copymode
def copy(src, dst, *, follow_symlinks=True):"""Copy data and mode bits ("cp src dst"). Return the file's destination.The destination may be a directory.If follow_symlinks is false, symlinks won't be followed. Thisresembles GNU's "cp -P src dst".If source and destination are the same file, a SameFileError will beraised."""if os.path.isdir(dst):dst = os.path.join(dst, os.path.basename(src))copyfile(src, dst, follow_symlinks=follow_symlinks)copymode(src, dst, follow_symlinks=follow_symlinks)return dst
6 shutil.copy2(src,dst) #复制文件的内容以及文件的所有状态信息。先copyfile后copystat
def copy2(src, dst, *, follow_symlinks=True):"""Copy data and all stat info ("cp -p src dst"). Return the file'sdestination."The destination may be a directory.If follow_symlinks is false, symlinks won't be followed. Thisresembles GNU's "cp -P src dst"."""if os.path.isdir(dst):dst = os.path.join(dst, os.path.basename(src))copyfile(src, dst, follow_symlinks=follow_symlinks)copystat(src, dst, follow_symlinks=follow_symlinks)return dst
7 shutil.copytree(src, dst, symlinks=False, ignore=None, copy_function=copy2,ignore_dangling_symlinks=False) #递归的复制文件内容及状态信息
def copytree(src, dst, symlinks=False, ignore=None, copy_function=copy2,ignore_dangling_symlinks=False):"""Recursively copy a directory tree.The destination directory must not already exist.If exception(s) occur, an Error is raised with a list of reasons.If the optional symlinks flag is true, symbolic links in thesource tree result in symbolic links in the destination tree; ifit is false, the contents of the files pointed to by symboliclinks are copied. If the file pointed by the symlink doesn'texist, an exception will be added in the list of errors raised inan Error exception at the end of the copy process.You can set the optional ignore_dangling_symlinks flag to true if youwant to silence this exception. Notice that this has no effect onplatforms that don't support os.symlink.The optional ignore argument is a callable. If given, itis called with the `src` parameter, which is the directorybeing visited by copytree(), and `names` which is the list of`src` contents, as returned by os.listdir():callable(src, names) -> ignored_namesSince copytree() is called recursively, the callable will becalled once for each directory that is copied. It returns alist of names relative to the `src` directory that shouldnot be copied.The optional copy_function argument is a callable that will be usedto copy each file. It will be called with the source path and thedestination path as arguments. By default, copy2() is used, but anyfunction that supports the same signature (like copy()) can be used."""names = os.listdir(src)if ignore is not None:ignored_names = ignore(src, names)else:ignored_names = set()os.makedirs(dst)errors = []for name in names:if name in ignored_names:continuesrcname = os.path.join(src, name)dstname = os.path.join(dst, name)try:if os.path.islink(srcname):linkto = os.readlink(srcname)if symlinks:# We can't just leave it to `copy_function` because legacy# code with a custom `copy_function` may rely on copytree# doing the right thing. os.symlink(linkto, dstname)copystat(srcname, dstname, follow_symlinks=not symlinks)else:# ignore dangling symlink if the flag is onif not os.path.exists(linkto) and ignore_dangling_symlinks:continue# otherwise let the copy occurs. copy2 will raise an errorif os.path.isdir(srcname):copytree(srcname, dstname, symlinks, ignore,copy_function)else:copy_function(srcname, dstname)elif os.path.isdir(srcname):copytree(srcname, dstname, symlinks, ignore, copy_function)else:# Will raise a SpecialFileError for unsupported file types copy_function(srcname, dstname)# catch the Error from the recursive copytree so that we can# continue with other filesexcept Error as err:errors.extend(err.args[0])except OSError as why:errors.append((srcname, dstname, str(why)))try:copystat(src, dst)except OSError as why:# Copying file access times may fail on Windowsif getattr(why, 'winerror', None) is None:errors.append((src, dst, str(why)))if errors:raise Error(errors)return dst# version vulnerable to race conditions
[root@slyoyo python_test]# tree copytree_test/ copytree_test/ └── test├── test1├── test2└── hahaha[root@slyoyo test]# ls -l total 0 -rw-r--r--. 1 python python 0 May 14 19:36 hahaha -rw-r--r--. 1 python python 0 May 14 19:36 test1 -rw-r--r--. 1 root root 0 May 14 19:36 test2>>> shutil.copytree('copytree_test','copytree_copy') 'copytree_copy'[root@slyoyo python_test]# ls -l total 12 drwxr-xr-x. 3 root root 4096 May 14 19:36 copytree_copy drwxr-xr-x. 3 root root 4096 May 14 19:36 copytree_test -rw-r--r--. 1 python python 79 May 14 05:17 test1 -rw-r--r--. 1 root root 0 May 14 19:10 test2 [root@slyoyo python_test]# tree copytree_copy/ copytree_copy/ └── test├── hahaha├── test1└── test2
8 shutil.rmtree(path, ignore_errors=False, οnerrοr=None) #递归地删除文件
def rmtree(path, ignore_errors=False, οnerrοr=None):"""Recursively delete a directory tree.If ignore_errors is set, errors are ignored; otherwise, if onerroris set, it is called to handle the error with arguments (func,path, exc_info) where func is platform and implementation dependent;path is the argument to that function that caused it to fail; andexc_info is a tuple returned by sys.exc_info(). If ignore_errorsis false and onerror is None, an exception is raised."""if ignore_errors:def onerror(*args):passelif onerror is None:def onerror(*args):raiseif _use_fd_functions:# While the unsafe rmtree works fine on bytes, the fd based does not.if isinstance(path, bytes):path = os.fsdecode(path)# Note: To guard against symlink races, we use the standard# lstat()/open()/fstat() trick.try:orig_st = os.lstat(path)except Exception:onerror(os.lstat, path, sys.exc_info())returntry:fd = os.open(path, os.O_RDONLY)except Exception:onerror(os.lstat, path, sys.exc_info())returntry:if os.path.samestat(orig_st, os.fstat(fd)):_rmtree_safe_fd(fd, path, onerror)try:os.rmdir(path)except OSError:onerror(os.rmdir, path, sys.exc_info())else:try:# symlinks to directories are forbidden, see bug #1669raise OSError("Cannot call rmtree on a symbolic link")except OSError:onerror(os.path.islink, path, sys.exc_info())finally:os.close(fd)else:return _rmtree_unsafe(path, onerror)# Allow introspection of whether or not the hardening against symlink # attacks is supported on the current platform rmtree.avoids_symlink_attacks = _use_fd_functions
9 shutil.move(src, dst) #递归的移动文件
def move(src, dst):"""Recursively move a file or directory to another location. This issimilar to the Unix "mv" command. Return the file or directory'sdestination.If the destination is a directory or a symlink to a directory, the sourceis moved inside the directory. The destination path must not alreadyexist.If the destination already exists but is not a directory, it may beoverwritten depending on os.rename() semantics.If the destination is on our current filesystem, then rename() is used.Otherwise, src is copied to the destination and then removed. Symlinks arerecreated under the new name if os.rename() fails because of crossfilesystem renames.A lot more could be done here... A look at a mv.c shows a lot ofthe issues this implementation glosses over."""real_dst = dstif os.path.isdir(dst):if _samefile(src, dst):# We might be on a case insensitive filesystem,# perform the rename anyway. os.rename(src, dst)returnreal_dst = os.path.join(dst, _basename(src))if os.path.exists(real_dst):raise Error("Destination path '%s' already exists" % real_dst)try:os.rename(src, real_dst)except OSError:if os.path.islink(src):linkto = os.readlink(src)os.symlink(linkto, real_dst)os.unlink(src)elif os.path.isdir(src):if _destinsrc(src, dst):raise Error("Cannot move a directory '%s' into itself '%s'." % (src, dst))copytree(src, real_dst, symlinks=True)rmtree(src)else:copy2(src, real_dst)os.unlink(src)return real_dst
10 make_archive(base_name, format, root_dir=None, base_dir=None, verbose=0,dry_run=0, owner=None, group=None, logger=None) #压缩打包
def make_archive(base_name, format, root_dir=None, base_dir=None, verbose=0,dry_run=0, owner=None, group=None, logger=None):"""Create an archive file (eg. zip or tar).'base_name' is the name of the file to create, minus any format-specificextension; 'format' is the archive format: one of "zip", "tar", "bztar"or "gztar".'root_dir' is a directory that will be the root directory of thearchive; ie. we typically chdir into 'root_dir' before creating thearchive. 'base_dir' is the directory where we start archiving from;ie. 'base_dir' will be the common prefix of all files anddirectories in the archive. 'root_dir' and 'base_dir' both defaultto the current directory. Returns the name of the archive file.'owner' and 'group' are used when creating a tar archive. By default,uses the current owner and group."""save_cwd = os.getcwd()if root_dir is not None:if logger is not None:logger.debug("changing into '%s'", root_dir)base_name = os.path.abspath(base_name)if not dry_run:os.chdir(root_dir)if base_dir is None:base_dir = os.curdirkwargs = {'dry_run': dry_run, 'logger': logger}try:format_info = _ARCHIVE_FORMATS[format]except KeyError:raise ValueError("unknown archive format '%s'" % format)func = format_info[0]for arg, val in format_info[1]:kwargs[arg] = valif format != 'zip':kwargs['owner'] = ownerkwargs['group'] = grouptry:filename = func(base_name, base_dir, **kwargs)finally:if root_dir is not None:if logger is not None:logger.debug("changing back to '%s'", save_cwd)os.chdir(save_cwd)return filename
base_name： 压缩打包后的文件名或者路径名
format： 压缩或者打包格式 "zip", "tar", "bztar"or "gztar"
root_dir : 将哪个目录或者文件打包（也就是源文件）
>>> shutil.make_archive('tarball','gztar',root_dir='copytree_test')[root@slyoyo python_test]# ls -l total 12 drwxr-xr-x. 3 root root 4096 May 14 19:36 copytree_copy drwxr-xr-x. 3 root root 4096 May 14 19:36 copytree_test -rw-r--r--. 1 root root 0 May 14 21:12 tarball.tar.gz -rw-r--r--. 1 python python 79 May 14 05:17 test1 -rw-r--r--. 1 root root 0 May 14 19:10 test2
