Ubuntu Manpage: chflags, lchflags, fchflags, chflagsat

Provided by: freebsd-manpages_11.1-3_all

NAME

     chflags, lchflags, fchflags, chflagsat — set file flags

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/stat.h>
     #include <unistd.h>

     int
     chflags(const char *path, unsigned long flags);

     int
     lchflags(const char *path, unsigned long flags);

     int
     fchflags(int fd, unsigned long flags);

     int
     chflagsat(int fd, const char *path, unsigned long flags, int atflag);

DESCRIPTION

The file whose name is given by path or referenced by the descriptor fd has its flags
changed to flags.

The lchflags() system call is like chflags() except in the case where the named file is a
symbolic link, in which case lchflags() will change the flags of the link itself, rather
than the file it points to.

The chflagsat() is equivalent to either chflags() or lchflags() depending on the atflag
except in the case where path specifies a relative path. In this case the file to be
changed is determined relative to the directory associated with the file descriptor fd
instead of the current working directory. The values for the atflag are constructed by a
bitwise-inclusive OR of flags from the following list, defined in <fcntl.h>:

AT_SYMLINK_NOFOLLOW
If path names a symbolic link, then the flags of the symbolic link are changed.

If chflagsat() is passed the special value AT_FDCWD in the fd parameter, the current working
directory is used. If also atflag is zero, the behavior is identical to a call to
chflags().

The flags specified are formed by or'ing the following values

SF_APPEND The file may only be appended to.
SF_ARCHIVED The file has been archived. This flag means the opposite of the DOS,
Windows and CIFS FILE_ATTRIBUTE_ARCHIVE attribute. This flag has been
deprecated, and may be removed in a future release.
SF_IMMUTABLE The file may not be changed.
SF_NOUNLINK The file may not be renamed or deleted.
SF_SNAPSHOT The file is a snapshot file.
UF_APPEND The file may only be appended to.
UF_ARCHIVE The file needs to be archived. This flag has the same meaning as the
DOS, Windows and CIFS FILE_ATTRIBUTE_ARCHIVE attribute. Filesystems in
FreeBSD may or may not have special handling for this flag. For
instance, ZFS tracks changes to files and will set this bit when a file
is updated. UFS only stores the flag, and relies on the application to
change it when needed.
UF_HIDDEN The file may be hidden from directory listings at the application's
discretion. The file has the DOS, Windows and CIFS
FILE_ATTRIBUTE_HIDDEN attribute.
UF_IMMUTABLE The file may not be changed.
UF_NODUMP Do not dump the file.
UF_NOUNLINK The file may not be renamed or deleted.
UF_OFFLINE The file is offline, or has the Windows and CIFS FILE_ATTRIBUTE_OFFLINE
attribute. Filesystems in FreeBSD store and display this flag, but do
not provide any special handling when it is set.
UF_OPAQUE The directory is opaque when viewed through a union stack.
UF_READONLY The file is read only, and may not be written or appended. Filesystems
may use this flag to maintain compatibility with the DOS, Windows and
CIFS FILE_ATTRIBUTE_READONLY attribute.
UF_REPARSE The file contains a Windows reparse point and has the Windows and CIFS
FILE_ATTRIBUTE_REPARSE_POINT attribute.
UF_SPARSE The file has the Windows FILE_ATTRIBUTE_SPARSE_FILE attribute. This may
also be used by a filesystem to indicate a sparse file.
UF_SYSTEM The file has the DOS, Windows and CIFS FILE_ATTRIBUTE_SYSTEM attribute.
Filesystems in FreeBSD may store and display this flag, but do not
provide any special handling when it is set.

If one of SF_IMMUTABLE, SF_APPEND, or SF_NOUNLINK is set a non-super-user cannot change any
flags and even the super-user can change flags only if securelevel is 0. (See init(8) for
details.)

The UF_IMMUTABLE, UF_APPEND, UF_NOUNLINK, UF_NODUMP, and UF_OPAQUE flags may be set or unset
by either the owner of a file or the super-user.

The SF_IMMUTABLE, SF_APPEND, SF_NOUNLINK, and SF_ARCHIVED flags may only be set or unset by
the super-user. Attempts to toggle these flags by non-super-users are rejected. These
flags may be set at any time, but normally may only be unset when the system is in single-
user mode. (See init(8) for details.)

The implementation of all flags is filesystem-dependent. See the description of the
UF_ARCHIVE flag above for one example of the differences in behavior. Care should be
exercised when writing applications to account for support or lack of support of these flags
in various filesystems.

The SF_SNAPSHOT flag is maintained by the system and cannot be toggled.

RETURN VALUES

     Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and
     the global variable errno is set to indicate the error.

ERRORS

     The chflags() system call will fail if:

     [ENOTDIR]          A component of the path prefix is not a directory.

     [ENAMETOOLONG]     A component of a pathname exceeded 255 characters, or an entire path name
                        exceeded 1023 characters.

     [ENOENT]           The named file does not exist.

     [EACCES]           Search permission is denied for a component of the path prefix.

     [ELOOP]            Too many symbolic links were encountered in translating the pathname.

     [EPERM]            The effective user ID does not match the owner of the file and the
                        effective user ID is not the super-user.

     [EPERM]            One of SF_IMMUTABLE, SF_APPEND, or SF_NOUNLINK is set and the user is
                        either not the super-user or securelevel is greater than 0.

     [EPERM]            A non-super-user attempted to toggle one of SF_ARCHIVED, SF_IMMUTABLE,
                        SF_APPEND, or SF_NOUNLINK.

     [EPERM]            An attempt was made to toggle the SF_SNAPSHOT flag.

     [EROFS]            The named file resides on a read-only file system.

     [EFAULT]           The path argument points outside the process's allocated address space.

     [EIO]              An I/O error occurred while reading from or writing to the file system.

     [EOPNOTSUPP]       The underlying file system does not support file flags, or does not
                        support all of the flags set in flags.

     The fchflags() system call will fail if:

     [EBADF]            The descriptor is not valid.

     [EINVAL]           The fd argument refers to a socket, not to a file.

     [EPERM]            The effective user ID does not match the owner of the file and the
                        effective user ID is not the super-user.

     [EPERM]            One of SF_IMMUTABLE, SF_APPEND, or SF_NOUNLINK is set and the user is
                        either not the super-user or securelevel is greater than 0.

     [EPERM]            A non-super-user attempted to toggle one of SF_ARCHIVED, SF_IMMUTABLE,
                        SF_APPEND, or SF_NOUNLINK.

     [EPERM]            An attempt was made to toggle the SF_SNAPSHOT flag.

     [EROFS]            The file resides on a read-only file system.

     [EIO]              An I/O error occurred while reading from or writing to the file system.

     [EOPNOTSUPP]       The underlying file system does not support file flags, or does not
                        support all of the flags set in flags.

HISTORY

     The chflags() and fchflags() system calls first appeared in 4.4BSD.  The lchflags() system
     call first appeared in FreeBSD 5.0.  The chflagsat() system call first appeared in
     FreeBSD 10.0.