229 lines
6.5 KiB
Groff
229 lines
6.5 KiB
Groff
.\" $NetBSD: chmod.2,v 1.25 2003/04/16 13:34:51 wiz Exp $
|
|
.\"
|
|
.\" Copyright (c) 1980, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the University of
|
|
.\" California, Berkeley and its contributors.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)chmod.2 8.1 (Berkeley) 6/4/93
|
|
.\"
|
|
.Dd June 4, 1993
|
|
.Dt CHMOD 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm chmod ,
|
|
.Nm lchmod ,
|
|
.Nm fchmod
|
|
.Nd change mode of file
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In sys/stat.h
|
|
.Ft int
|
|
.Fn chmod "const char *path" "mode_t mode"
|
|
.Ft int
|
|
.Fn lchmod "const char *path" "mode_t mode"
|
|
.Ft int
|
|
.Fn fchmod "int fd" "mode_t mode"
|
|
.Sh DESCRIPTION
|
|
The function
|
|
.Fn chmod
|
|
sets the file permission bits
|
|
of the file
|
|
specified by the pathname
|
|
.Fa path
|
|
to
|
|
.Fa mode .
|
|
.Fn fchmod
|
|
sets the permission bits of the specified
|
|
file descriptor
|
|
.Fa fd .
|
|
.Fn lchmod
|
|
is like
|
|
.Fn chmod
|
|
except in the case where the named file is a symbolic link,
|
|
in which case
|
|
.Fn lchmod
|
|
sets the permission bits of the link,
|
|
while
|
|
.Fn chmod
|
|
sets the bits of the file the link references.
|
|
.Fn chmod
|
|
verifies that the process owner (user) either owns
|
|
the file specified by
|
|
.Fa path
|
|
(or
|
|
.Fa fd ) ,
|
|
or
|
|
is the super-user.
|
|
A mode is created from
|
|
.Em or'd
|
|
permission bit masks
|
|
defined in
|
|
.Aq Pa sys/stat.h :
|
|
.Bd -literal -offset indent -compact
|
|
#define S_IRWXU 0000700 /* RWX mask for owner */
|
|
#define S_IRUSR 0000400 /* R for owner */
|
|
#define S_IWUSR 0000200 /* W for owner */
|
|
#define S_IXUSR 0000100 /* X for owner */
|
|
|
|
#define S_IRWXG 0000070 /* RWX mask for group */
|
|
#define S_IRGRP 0000040 /* R for group */
|
|
#define S_IWGRP 0000020 /* W for group */
|
|
#define S_IXGRP 0000010 /* X for group */
|
|
|
|
#define S_IRWXO 0000007 /* RWX mask for other */
|
|
#define S_IROTH 0000004 /* R for other */
|
|
#define S_IWOTH 0000002 /* W for other */
|
|
#define S_IXOTH 0000001 /* X for other */
|
|
|
|
#define S_ISUID 0004000 /* set user id on execution */
|
|
#define S_ISGID 0002000 /* set group id on execution */
|
|
#define S_ISVTX 0001000 /* save swapped text even after use */
|
|
.Ed
|
|
.Pp
|
|
The
|
|
.Dv ISVTX
|
|
(the
|
|
.Em sticky bit )
|
|
indicates to the system which executable files are shareable (the
|
|
default) and the system maintains the program text of the files
|
|
in the swap area.
|
|
The sticky bit may only be set by the super user
|
|
on shareable executable files.
|
|
.Pp
|
|
If mode
|
|
.Dv ISVTX
|
|
(the `sticky bit') is set on a directory,
|
|
an unprivileged user may not delete or rename
|
|
files of other users in that directory.
|
|
The sticky bit may be set by any user on a directory which the user
|
|
owns or has appropriate permissions.
|
|
For more details of the properties of the sticky bit, see
|
|
.Xr sticky 8 .
|
|
.Pp
|
|
Changing the owner of a file
|
|
turns off the set-user-id and set-group-id bits;
|
|
writing to a file
|
|
turns off the set-user-id and set-group-id bits
|
|
unless the user is the super-user.
|
|
This makes the system somewhat more secure
|
|
by protecting set-user-id (set-group-id) files
|
|
from remaining set-user-id (set-group-id) if they are modified,
|
|
at the expense of a degree of compatibility.
|
|
.Sh RETURN VALUES
|
|
Upon successful completion, a value of 0 is returned.
|
|
Otherwise, a value of -1 is returned and
|
|
.Va errno
|
|
is set to indicate the error.
|
|
.Sh ERRORS
|
|
.Fn chmod
|
|
and
|
|
.Fn lchmod
|
|
will fail and the file mode will be unchanged 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 super-user.
|
|
.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 I/O error occurred while reading from or writing to the file system.
|
|
.It Bq Er EFTYPE
|
|
The effective user ID is not the super-user, the
|
|
.Fa mode
|
|
includes the sticky bit
|
|
.Pq Dv S_ISVTX ,
|
|
and
|
|
.Fa path
|
|
does not refer to a directory.
|
|
.El
|
|
.Pp
|
|
.Fn fchmod
|
|
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 EROFS
|
|
The file resides on a read-only file system.
|
|
.It Bq Er EIO
|
|
An I/O error occurred while reading from or writing to the file system.
|
|
.It Bq Er EFTYPE
|
|
The effective user ID is not the super-user, the
|
|
.Fa mode
|
|
includes the sticky bit
|
|
.Pq Dv S_ISVTX ,
|
|
and
|
|
.Fa fd
|
|
does not refer to a directory.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr chmod 1 ,
|
|
.Xr chflags 2 ,
|
|
.Xr chown 2 ,
|
|
.Xr open 2 ,
|
|
.Xr stat 2 ,
|
|
.Xr symlink 7 ,
|
|
.Xr sticky 8
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn chmod
|
|
function conforms to
|
|
.St -p1003.1-90 .
|
|
.Sh HISTORY
|
|
The
|
|
.Fn fchmod
|
|
function call
|
|
appeared in
|
|
.Bx 4.2 .
|
|
The
|
|
.Fn lchmod
|
|
function call appeared in
|
|
.Nx 1.3 .
|