Edit File: stat.txt
:mod:`stat` --- Interpreting :func:`stat` results ================================================= .. module:: stat :synopsis: Utilities for interpreting the results of os.stat(), os.lstat() and os.fstat(). .. sectionauthor:: Skip Montanaro <skip@automatrix.com> The :mod:`stat` module defines constants and functions for interpreting the results of :func:`os.stat`, :func:`os.fstat` and :func:`os.lstat` (if they exist). For complete details about the :cfunc:`stat`, :cfunc:`fstat` and :cfunc:`lstat` calls, consult the documentation for your system. The :mod:`stat` module defines the following functions to test for specific file types: .. function:: S_ISDIR(mode) Return non-zero if the mode is from a directory. .. function:: S_ISCHR(mode) Return non-zero if the mode is from a character special device file. .. function:: S_ISBLK(mode) Return non-zero if the mode is from a block special device file. .. function:: S_ISREG(mode) Return non-zero if the mode is from a regular file. .. function:: S_ISFIFO(mode) Return non-zero if the mode is from a FIFO (named pipe). .. function:: S_ISLNK(mode) Return non-zero if the mode is from a symbolic link. .. function:: S_ISSOCK(mode) Return non-zero if the mode is from a socket. Two additional functions are defined for more general manipulation of the file's mode: .. function:: S_IMODE(mode) Return the portion of the file's mode that can be set by :func:`os.chmod`\ ---that is, the file's permission bits, plus the sticky bit, set-group-id, and set-user-id bits (on systems that support them). .. function:: S_IFMT(mode) Return the portion of the file's mode that describes the file type (used by the :func:`S_IS\*` functions above). Normally, you would use the :func:`os.path.is\*` functions for testing the type of a file; the functions here are useful when you are doing multiple tests of the same file and wish to avoid the overhead of the :cfunc:`stat` system call for each test. These are also useful when checking for information about a file that isn't handled by :mod:`os.path`, like the tests for block and character devices. All the variables below are simply symbolic indexes into the 10-tuple returned by :func:`os.stat`, :func:`os.fstat` or :func:`os.lstat`. .. data:: ST_MODE Inode protection mode. .. data:: ST_INO Inode number. .. data:: ST_DEV Device inode resides on. .. data:: ST_NLINK Number of links to the inode. .. data:: ST_UID User id of the owner. .. data:: ST_GID Group id of the owner. .. data:: ST_SIZE Size in bytes of a plain file; amount of data waiting on some special files. .. data:: ST_ATIME Time of last access. .. data:: ST_MTIME Time of last modification. .. data:: 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 :func:`os.stat`, :func:`os.fstat`, or :func:`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 :data:`ST_MODE` field. Use of the functions above is more portable than use of the first set of flags: .. data:: S_IFMT Bit mask for the file type bit fields. .. data:: S_IFSOCK Socket. .. data:: S_IFLNK Symbolic link. .. data:: S_IFREG Regular file. .. data:: S_IFBLK Block device. .. data:: S_IFDIR Directory. .. data:: S_IFCHR Character device. .. data:: S_IFIFO FIFO. The following flags can also be used in the *mode* argument of :func:`os.chmod`: .. data:: S_ISUID Set UID bit. .. data:: 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 :data:`S_ISGID` bit set. For a file that does not have the group execution bit (:data:`S_IXGRP`) set, the set-group-ID bit indicates mandatory file/record locking (see also :data:`S_ENFMT`). .. data:: 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. .. data:: S_IRWXU Mask for file owner permissions. .. data:: S_IRUSR Owner has read permission. .. data:: S_IWUSR Owner has write permission. .. data:: S_IXUSR Owner has execute permission. .. data:: S_IRWXG Mask for group permissions. .. data:: S_IRGRP Group has read permission. .. data:: S_IWGRP Group has write permission. .. data:: S_IXGRP Group has execute permission. .. data:: S_IRWXO Mask for permissions for others (not in group). .. data:: S_IROTH Others have read permission. .. data:: S_IWOTH Others have write permission. .. data:: S_IXOTH Others have execute permission. .. data:: S_ENFMT System V file locking enforcement. This flag is shared with :data:`S_ISGID`: file/record locking is enforced on files that do not have the group execution bit (:data:`S_IXGRP`) set. .. data:: S_IREAD Unix V7 synonym for :data:`S_IRUSR`. .. data:: S_IWRITE Unix V7 synonym for :data:`S_IWUSR`. .. data:: S_IEXEC Unix V7 synonym for :data:`S_IXUSR`. Example:: import os, sys from stat import * def 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_MODE] if S_ISDIR(mode): # It's a directory, recurse into it walktree(pathname, callback) elif S_ISREG(mode): # It's a file, call the callback function callback(pathname) else: # Unknown file type, print a message print 'Skipping %s' % pathname def visitfile(file): print 'visiting', file if __name__ == '__main__': walktree(sys.argv[1], visitfile)
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