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# 10.3. `stat` — Interpreting `stat()` results

Source code: Lib/stat.py

The `stat` module defines constants and functions for interpreting the results of `os.stat()`, `os.fstat()` and `os.lstat()` (if they exist). For complete details about the `stat()`, `fstat()` and `lstat()` calls, consult the documentation for your system.

The `stat` module defines the following functions to test for specific file types:

stat.S_ISDIR(mode)

  Return non-zero if the mode is from a directory.

stat.S_ISCHR(mode)

  Return non-zero if the mode is from a character special device file.

stat.S_ISBLK(mode)

  Return non-zero if the mode is from a block special device file.

stat.S_ISREG(mode)

  Return non-zero if the mode is from a regular file.

stat.S_ISFIFO(mode)

  Return non-zero if the mode is from a FIFO (named pipe).

stat.S_ISLNK(mode)

  Return non-zero if the mode is from a symbolic link.

stat.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:

stat.S_IMODE(mode)

  Return the portion of the file’s mode that can be set by `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).

stat.S_IFMT(mode)

  Return the portion of the file’s mode that describes the file type (used by the `S_IS*()` functions above).

Normally, you would use the `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 `stat()` system call for each test. These are also useful when checking for information about a file that isn’t handled by `os.path`, like the tests for block and character devices.

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)

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.