Ubuntu Manpage: chflags, lchflags, fchflags, chflagsat

Provided by: freebsd-manpages_12.2-1_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SF_ARCHIVED The file has been archived.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.

       [EINTEGRITY]       Corrupted data was detected while reading from 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.

       [EINTEGRITY]       Corrupted data was detected while reading from 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.

Debian                                           March 30, 2020                                       CHFLAGS(2)