337 lines
7.4 KiB
ReStructuredText
337 lines
7.4 KiB
ReStructuredText
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:mod:`stat` --- Interpreting :func:`stat` results
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=================================================
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.. module:: stat
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:synopsis: Utilities for interpreting the results of os.stat(), os.lstat() and os.fstat().
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.. sectionauthor:: Skip Montanaro <skip@automatrix.com>
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The :mod:`stat` module defines constants and functions for interpreting the
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results of :func:`os.stat`, :func:`os.fstat` and :func:`os.lstat` (if they
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exist). For complete details about the :cfunc:`stat`, :cfunc:`fstat` and
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:cfunc:`lstat` calls, consult the documentation for your system.
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The :mod:`stat` module defines the following functions to test for specific file
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types:
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.. function:: S_ISDIR(mode)
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Return non-zero if the mode is from a directory.
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.. function:: S_ISCHR(mode)
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Return non-zero if the mode is from a character special device file.
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.. function:: S_ISBLK(mode)
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Return non-zero if the mode is from a block special device file.
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.. function:: S_ISREG(mode)
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Return non-zero if the mode is from a regular file.
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.. function:: S_ISFIFO(mode)
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Return non-zero if the mode is from a FIFO (named pipe).
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.. function:: S_ISLNK(mode)
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Return non-zero if the mode is from a symbolic link.
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.. function:: S_ISSOCK(mode)
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Return non-zero if the mode is from a socket.
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Two additional functions are defined for more general manipulation of the file's
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mode:
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.. function:: S_IMODE(mode)
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Return the portion of the file's mode that can be set by :func:`os.chmod`\
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---that is, the file's permission bits, plus the sticky bit, set-group-id, and
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set-user-id bits (on systems that support them).
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.. function:: S_IFMT(mode)
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Return the portion of the file's mode that describes the file type (used by the
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:func:`S_IS\*` functions above).
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Normally, you would use the :func:`os.path.is\*` functions for testing the type
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of a file; the functions here are useful when you are doing multiple tests of
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the same file and wish to avoid the overhead of the :cfunc:`stat` system call
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for each test. These are also useful when checking for information about a file
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that isn't handled by :mod:`os.path`, like the tests for block and character
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devices.
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Example::
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import os, sys
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from stat import *
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def walktree(top, callback):
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'''recursively descend the directory tree rooted at top,
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calling the callback function for each regular file'''
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for f in os.listdir(top):
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pathname = os.path.join(top, f)
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mode = os.stat(pathname)[ST_MODE]
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if S_ISDIR(mode):
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# It's a directory, recurse into it
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walktree(pathname, callback)
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elif S_ISREG(mode):
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# It's a file, call the callback function
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callback(pathname)
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else:
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# Unknown file type, print a message
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print 'Skipping %s' % pathname
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def visitfile(file):
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print 'visiting', file
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if __name__ == '__main__':
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walktree(sys.argv[1], visitfile)
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All the variables below are simply symbolic indexes into the 10-tuple returned
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by :func:`os.stat`, :func:`os.fstat` or :func:`os.lstat`.
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.. data:: ST_MODE
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Inode protection mode.
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.. data:: ST_INO
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Inode number.
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.. data:: ST_DEV
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Device inode resides on.
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.. data:: ST_NLINK
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Number of links to the inode.
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.. data:: ST_UID
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User id of the owner.
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.. data:: ST_GID
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Group id of the owner.
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.. data:: ST_SIZE
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Size in bytes of a plain file; amount of data waiting on some special files.
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.. data:: ST_ATIME
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Time of last access.
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.. data:: ST_MTIME
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Time of last modification.
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.. data:: ST_CTIME
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The "ctime" as reported by the operating system. On some systems (like Unix) is
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the time of the last metadata change, and, on others (like Windows), is the
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creation time (see platform documentation for details).
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The interpretation of "file size" changes according to the file type. For plain
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files this is the size of the file in bytes. For FIFOs and sockets under most
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flavors of Unix (including Linux in particular), the "size" is the number of
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bytes waiting to be read at the time of the call to :func:`os.stat`,
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:func:`os.fstat`, or :func:`os.lstat`; this can sometimes be useful, especially
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for polling one of these special files after a non-blocking open. The meaning
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of the size field for other character and block devices varies more, depending
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on the implementation of the underlying system call.
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The variables below define the flags used in the :data:`ST_MODE` field.
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Use of the functions above is more portable than use of the first set of flags:
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.. data:: S_IFMT
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Bit mask for the file type bit fields.
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.. data:: S_IFSOCK
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Socket.
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.. data:: S_IFLNK
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Symbolic link.
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.. data:: S_IFREG
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Regular file.
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.. data:: S_IFBLK
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Block device.
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.. data:: S_IFDIR
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Directory.
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.. data:: S_IFCHR
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Character device.
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.. data:: S_IFIFO
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FIFO.
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The following flags can also be used in the *mode* argument of :func:`os.chmod`:
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.. data:: S_ISUID
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Set UID bit.
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.. data:: S_ISGID
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Set-group-ID bit. This bit has several special uses. For a directory
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it indicates that BSD semantics is to be used for that directory:
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files created there inherit their group ID from the directory, not
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from the effective group ID of the creating process, and directories
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created there will also get the :data:`S_ISGID` bit set. For a
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file that does not have the group execution bit (:data:`S_IXGRP`)
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set, the set-group-ID bit indicates mandatory file/record locking
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(see also :data:`S_ENFMT`).
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.. data:: S_ISVTX
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Sticky bit. When this bit is set on a directory it means that a file
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in that directory can be renamed or deleted only by the owner of the
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file, by the owner of the directory, or by a privileged process.
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.. data:: S_IRWXU
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Mask for file owner permissions.
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.. data:: S_IRUSR
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Owner has read permission.
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.. data:: S_IWUSR
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Owner has write permission.
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.. data:: S_IXUSR
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Owner has execute permission.
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.. data:: S_IRWXG
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Mask for group permissions.
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.. data:: S_IRGRP
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Group has read permission.
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.. data:: S_IWGRP
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Group has write permission.
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.. data:: S_IXGRP
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Group has execute permission.
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.. data:: S_IRWXO
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Mask for permissions for others (not in group).
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.. data:: S_IROTH
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Others have read permission.
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.. data:: S_IWOTH
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Others have write permission.
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.. data:: S_IXOTH
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Others have execute permission.
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.. data:: S_ENFMT
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System V file locking enforcement. This flag is shared with :data:`S_ISGID`:
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file/record locking is enforced on files that do not have the group
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execution bit (:data:`S_IXGRP`) set.
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.. data:: S_IREAD
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Unix V7 synonym for :data:`S_IRUSR`.
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.. data:: S_IWRITE
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Unix V7 synonym for :data:`S_IWUSR`.
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.. data:: S_IEXEC
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Unix V7 synonym for :data:`S_IXUSR`.
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The following flags can be used in the *flags* argument of :func:`os.chflags`:
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.. data:: UF_NODUMP
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Do not dump the file.
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.. data:: UF_IMMUTABLE
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The file may not be changed.
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.. data:: UF_APPEND
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The file may only be appended to.
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.. data:: UF_NOUNLINK
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The file may not be renamed or deleted.
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.. data:: UF_OPAQUE
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The directory is opaque when viewed through a union stack.
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.. data:: SF_ARCHIVED
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The file may be archived.
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.. data:: SF_IMMUTABLE
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The file may not be changed.
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.. data:: SF_APPEND
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The file may only be appended to.
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.. data:: SF_NOUNLINK
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The file may not be renamed or deleted.
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.. data:: SF_SNAPSHOT
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The file is a snapshot file.
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See the \*BSD or Mac OS systems man page :manpage:`chflags(2)` for more information.
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