stat模块中定义了许多的常量和函数，可以帮助解释 os.stat()、os.fstat()、os.lstat()等函数返回的 st_result 类型的对象。
通常使用 os.path.is*() 这类函数来测试一个文件的类型，这些方法对同一个文件进行多次测试时，stat()系统调用都是不可避免的开销。同时，有些信息是os.path.is*() 这类函数无法提供的，例如检测是否是块设备、字符设备等。
此时就可以使用 stat 模块及stat模块中的诸多功能，下面是一个例子：
import os, sys
import statdef walktree(top, callback):'''recursively descend the directory tree rooted at top,calling the callback function for each regular file'''for f in os.listdir(top):pathname = os.path.join(top, f)mode = os.stat(pathname).st_modeif stat.S_ISDIR(mode):# It's a directory, recurse into itwalktree(pathname, callback)elif stat.S_ISREG(mode):# It's a file, call the callback functioncallback(pathname)else:# Unknown file type, print a messageprint 'Skipping %s' % pathnamedef visitfile(file):print 'visiting', fileif __name__ == '__main__':walktree(sys.argv[1], visitfile)
该例子递归遍历命令行参数所指定的目录中的所有普通文件。
例：上面脚本的执行结果
# python stat_test.py data_structure/ visiting data_structure/a.out visiting data_structure/biThrTree.h visiting data_structure/biThrTree.c
stat 模块定义的用来测试文件类型的函数包括
stat.S_ISDIR(mode)- 判断文件是不是一个目录。
stat.S_ISCHR(mode)- 判断文件是不是一个字符型设备。
stat.S_ISBLK(mode)
判断文件是不是一个块设备。
stat.S_ISREG(mode)
判断mode是不是来自一个普通文件。
stat.S_ISFIFO(mode)
判断mode是不是来自一个FIFO（如：具名管道）
stat.S_ISLNK(mode)
判断mode是不是来自一个符号链接。
stat.S_ISSOCK(mode)
判断mode是不是来自一个套接字。
上面的这些函数，除了 S_ISDIR 和 S_ISREG，其他都只在 Unix 环境下才有效。
stat.S_IMODE(mode)- 返回 mode 中可以被 os.chmod() 函数设置的部分，在Unix平台上，包括：权限位、sticky bits，set-group-id位、set-uid-bit等。
stat.S_IFMT(mode) - 返回 mode 中描述文件类型（可以被S_IS*()函数使用）的部分。
All the variables below are simply symbolic indexes into the 10-tuple returned by os.stat(), os.fstat() or os.lstat().
- stat.ST_MODE
-
Inode protection mode.
- stat.ST_INO
-
Inode number.
- stat.ST_DEV
-
Device inode resides on.
- stat.ST_NLINK
-
Number of links to the inode.
- stat.ST_UID
-
User id of the owner.
- stat.ST_GID
-
Group id of the owner.
- stat.ST_SIZE
-
Size in bytes of a plain file; amount of data waiting on some special files.
- stat.ST_ATIME
-
Time of last access.
- stat.ST_MTIME
-
Time of last modification.
- stat.ST_CTIME
-
The “ctime” as reported by the operating system. On some systems (like Unix) is the time of the last metadata change, and, on others (like Windows), is the creation time (see platform documentation for details).
The interpretation of “file size” changes according to the file type. For plain files this is the size of the file in bytes. For FIFOs and sockets under most flavors of Unix (including Linux in particular), the “size” is the number of bytes waiting to be read at the time of the call to os.stat(), os.fstat(), or os.lstat(); this can sometimes be useful, especially for polling one of these special files after a non-blocking open. The meaning of the size field for other character and block devices varies more, depending on the implementation of the underlying system call.
The variables below define the flags used in the ST_MODE field.
Use of the functions above is more portable than use of the first set of flags:
- stat.S_IFSOCK
-
Socket.
- stat.S_IFLNK
-
Symbolic link.
- stat.S_IFREG
-
Regular file.
- stat.S_IFBLK
-
Block device.
- stat.S_IFDIR
-
Directory.
- stat.S_IFCHR
-
Character device.
- stat.S_IFIFO
-
FIFO.
The following flags can also be used in the mode argument of os.chmod():
- stat.S_ISUID
-
Set UID bit.
- stat.S_ISGID
-
Set-group-ID bit. This bit has several special uses. For a directory it indicates that BSD semantics is to be used for that directory: files created there inherit their group ID from the directory, not from the effective group ID of the creating process, and directories created there will also get the S_ISGID bit set. For a file that does not have the group execution bit (S_IXGRP) set, the set-group-ID bit indicates mandatory file/record locking (see also S_ENFMT).
- stat.S_ISVTX
-
Sticky bit. When this bit is set on a directory it means that a file in that directory can be renamed or deleted only by the owner of the file, by the owner of the directory, or by a privileged process.
- stat.S_IRWXU
-
Mask for file owner permissions.
- stat.S_IRUSR
-
Owner has read permission.
- stat.S_IWUSR
-
Owner has write permission.
- stat.S_IXUSR
-
Owner has execute permission.
- stat.S_IRWXG
-
Mask for group permissions.
- stat.S_IRGRP
-
Group has read permission.
- stat.S_IWGRP
-
Group has write permission.
- stat.S_IXGRP
-
Group has execute permission.
- stat.S_IRWXO
-
Mask for permissions for others (not in group).
- stat.S_IROTH
-
Others have read permission.
- stat.S_IWOTH
-
Others have write permission.
- stat.S_IXOTH
-
Others have execute permission.
- stat.S_ENFMT
-
System V file locking enforcement. This flag is shared with S_ISGID: file/record locking is enforced on files that do not have the group execution bit (S_IXGRP) set.
- stat.S_IREAD
-
Unix V7 synonym for S_IRUSR.
- stat.S_IWRITE
-
Unix V7 synonym for S_IWUSR.
- stat.S_IEXEC
-
Unix V7 synonym for S_IXUSR.
The following flags can be used in the flags argument of os.chflags():
- stat.UF_NODUMP
-
Do not dump the file.
- stat.UF_IMMUTABLE
-
The file may not be changed.
- stat.UF_APPEND
-
The file may only be appended to.
- stat.UF_OPAQUE
-
The directory is opaque when viewed through a union stack.
- stat.UF_NOUNLINK
-
The file may not be renamed or deleted.
- stat.UF_COMPRESSED
-
The file is stored compressed (Mac OS X 10.6+).
- stat.UF_HIDDEN
-
The file should not be displayed in a GUI (Mac OS X 10.5+).
- stat.SF_ARCHIVED
-
The file may be archived.
- stat.SF_IMMUTABLE
-
The file may not be changed.
- stat.SF_APPEND
-
The file may only be appended to.
- stat.SF_NOUNLINK
-
The file may not be renamed or deleted.
- stat.SF_SNAPSHOT
-
The file is a snapshot file.
See the *BSD or Mac OS systems man page chflags(2) for more information.
