.\"	$OpenBSD: chflags.2,v 1.22 2009/08/20 18:32:58 martynas Exp $
.\"	$NetBSD: chflags.2,v 1.6 1995/02/27 12:32:03 cgd Exp $
.\"
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.\"	@(#)chflags.2	8.1 (Berkeley) 6/9/93
.\"
.Dd $Mdocdate: August 20 2009 $
.Dt CHFLAGS 2
.Os
.Sh NAME
.Nm chflags ,
.Nm fchflags
.Nd set file flags
.Sh SYNOPSIS
.Fd #include <sys/stat.h>
.Fd #include <unistd.h>
.Ft int
.Fn chflags "const char *path"  "unsigned int flags"
.Ft int
.Fn fchflags "int fd" "unsigned int 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 .
.Pp
The flags specified are formed by
.Tn 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 SF_ARCHIVED
The file may be 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_IMMUTABLE
and
.Dv UF_APPEND
flags may be set or unset by either the owner of a file or the superuser.
.Pp
The
.Dv SF_ARCHIVED ,
.Dv SF_IMMUTABLE
and
.Dv SF_APPEND
flags may only be set or unset by the superuser.
They 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
.Dv {NAME_MAX}
characters, or an entire path name exceeded
.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 superuser, or the effective user ID
is not the superuser and at least one 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.
.It Bq Er EINVAL
The
.Fa flags
value is invalid.
.It Bq Er EINVAL
The descriptor references a block or character device and the effective
user ID is not the superuser.
.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 EINVAL
The descriptor references a block or character device and the effective
user ID is not the superuser.
.It Bq Er EINVAL
The
.Fa flags
value is invalid.
.It Bq Er EPERM
The effective user ID does not match the owner of the file and
the effective user ID is not the superuser, or the effective user ID
is not the superuser and at least one 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 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 init 8
.Sh HISTORY
The
.Fn chflags
and
.Fn fchflags
functions first appeared in
.Bx 4.4 .