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.\"	@(#)chflags.2	8.3 (Berkeley) 5/2/95
.\"
.Dd August 6, 2011
.Dt CHFLAGS 2
.Os
.Sh NAME
.Nm chflags ,
.Nm lchflags ,
.Nm fchflags
.Nd set file flags
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/stat.h
.In unistd.h
.Ft int
.Fn chflags "const char *path"  "u_long flags"
.Ft int
.Fn lchflags "const char *path"  "u_long flags"
.Ft int
.Fn fchflags "int fd" "u_long flags"
.Sh DESCRIPTION
The file whose name
is given by
.Fa path
or referenced by the descriptor
.Fa fd
has its flags changed to
.Fa flags .
For
.Fn lchflags ,
symbolic links are not traversed and thus their modes may be changed with
this call.
.Pp
The flags specified are formed by
.Em or Ns 'ing
the following values:
.Pp
.Bl -tag -width "SF_IMMUTABLE" -compact -offset indent
.It Dv UF_NODUMP
Do not dump the file.
.It Dv UF_IMMUTABLE
The file may not be changed.
.It Dv UF_APPEND
The file may only be appended to.
.It Dv UF_OPAQUE
The file (if a directory) is opaque for union mounts.
.It Dv SF_ARCHIVED
The file is archived.
.It Dv SF_IMMUTABLE
The file may not be changed.
.It Dv SF_APPEND
The file may only be appended to.
.El
.Pp
The
.Dv UF_NODUMP ,
.Dv UF_IMMUTABLE ,
.Dv UF_APPEND ,
and
.Dv UF_OPAQUE
flags may be set or unset by either the owner of a file or the super-user,
except on block and character devices, where only the super-user may set
or unset them.
.Pp
The
.Dv SF_ARCHIVED ,
.Dv SF_IMMUTABLE ,
and
.Dv SF_APPEND
flags may only be set or unset by the super-user.
These flags may be set at any time, but normally may only be unset when
the system is in single-user mode.
(See
.Xr init 8
for details.)
.Sh RETURN VALUES
Upon successful completion, a value of 0 is returned.
Otherwise, \-1 is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn chflags
will fail if:
.Bl -tag -width Er
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded
.Brq Dv NAME_MAX
characters, or an entire path name exceeded
.Brq Dv PATH_MAX
characters.
.It Bq Er ENOENT
The named file does not exist.
.It Bq Er EACCES
Search permission is denied for a component of the path prefix.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er EPERM
The effective user ID does not match the owner of the file and
the effective user ID is not the super-user, or
the effective user ID is not the super-user and one or more of the
super-user-only flags for the named file would be changed.
.It Bq Er EOPNOTSUPP
The named file resides on a file system that does not support file
flags.
.It Bq Er EROFS
The named file resides on a read-only file system.
.It Bq Er EFAULT
.Fa path
points outside the process's allocated address space.
.It Bq Er EIO
An
.Tn I/O
error occurred while reading from or writing to the file system.
.El
.Pp
.Fn fchflags
will fail if:
.Bl -tag -width Er
.It Bq Er EBADF
The descriptor is not valid.
.It Bq Er EINVAL
.Fa fd
refers to a socket, not to a file.
.It Bq Er EPERM
The effective user ID does not match the owner of the file and
the effective user ID is not the super-user, or
the effective user ID is not the super-user and one or more of the
super-user-only flags for the file would be changed.
.It Bq Er EOPNOTSUPP
The file resides on a file system that does not support file flags.
.It Bq Er EROFS
The file resides on a read-only file system.
.It Bq Er EIO
An
.Tn I/O
error occurred while reading from or writing to the file system.
.El
.Sh SEE ALSO
.Xr chflags 1 ,
.Xr stat 2 ,
.Xr stat_flags 3 ,
.Xr init 8 ,
.Xr mount_union 8
.Sh HISTORY
The
.Fn chflags
and
.Fn fchflags
functions first appeared in
.Bx 4.4 .
The
.Fn lchflags
function first appeared in
.Nx 1.5 .