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.
