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153 lines
5.0 KiB
Groff
153 lines
5.0 KiB
Groff
.\" Copyright (c) 1980, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)chmod.2 8.1 (Berkeley) 6/4/93
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.\"
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.TH CHMOD 2 "22 February 1996" GNO "System Calls"
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.SH NAME
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.BR chmod ,
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.BR fchmod
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\- change mode of file
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.SH SYNOPSIS
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#include <sys/stat.h>
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.sp 1
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int
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\fBchmod\fR (const char *\fIpath\fR, mode_t \fImode\fR);
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.br
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int
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\fBfchmod\fR (int \fIfd\fR, mode_t \fImode\fR);
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.SH DESCRIPTION
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The function
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.BR chmod
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sets the file permission bits
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of the file
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specified by the pathname
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.I path
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to
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.IR mode .
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.BR fchmod
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sets the permission bits of the specified
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file descriptor
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.IR fd .
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.BR chmod
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verifies that the process owner (user) either owns
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the file specified by
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.I path
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(or
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.IR fd )
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or
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is the super-user.
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A mode is created from
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.IR or'd
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permission bit masks
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defined in <sys/stat.h>:
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.nf
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#define S_IRWXU 0000700 /* RWX mask for owner */
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#define S_IRUSR 0000400 /* R for owner */
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#define S_IWUSR 0000200 /* W for owner */
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#define S_IXUSR 0000100 /* X for owner */
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#define S_IRWXG 0000070 /* RWX mask for group */
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#define S_IRGRP 0000040 /* R for group */
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#define S_IWGRP 0000020 /* W for group */
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#define S_IXGRP 0000010 /* X for group */
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#define S_IRWXO 0000007 /* RWX mask for other */
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#define S_IROTH 0000004 /* R for other */
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#define S_IWOTH 0000002 /* W for other */
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#define S_IXOTH 0000001 /* X for other */
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#define S_ISUID 0004000 /* set user id on execution */
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#define S_ISGID 0002000 /* set group id on execution */
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#define S_ISVTX 0001000 /* save swapped text even after use */
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.fi
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.LP
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The
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.BR ISVTX
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(the
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.IR sticky
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bit )
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indicates to the system which executable files are shareable (the
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default) and the system maintains the program text of the files
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in the swap area. The sticky bit may only be set by the super user
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on shareable executable files.
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.LP
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If mode
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.BR ISVTX
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(the `sticky bit') is set on a directory,
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an unprivileged user may not delete or rename
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files of other users in that directory. The sticky bit may be
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set by any user on a directory which the user owns or has appropriate
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permissions.
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For more details of the properties of the sticky bit, see
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.BR sticky (8).
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.LP
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Writing or changing the owner of a file
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turns off the set-user-id and set-group-id bits
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unless the user is the super-user.
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This makes the system somewhat more secure
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by protecting set-user-id (set-group-id) files
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from remaining set-user-id (set-group-id) if they are modified,
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at the expense of a degree of compatibility.
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.SH COMPATIBILITY
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The Orca/C implementation of
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.BR chmod
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interprets
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.IR mode
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as GS/OS access bits. In order to get this behavior with the GNO
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implementation, mode mapping must be turned off (see
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.BR mapMode (3)).
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.SH RETURN VALUES
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Upon successful completion, a value of 0 is returned.
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Otherwise, a value of -1 is returned and
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.IR errno
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is set to indicate the error.
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.SH BUGS
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Verification of the ownership of the target file is not currently checked
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under GNO. (This would matter only for Appleshare volumes.)
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.LP
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Due to GNO's underlying filesystems, the sticky bit is not implemented.
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.SH SEE ALSO
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.BR chmod (1),
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.BR open (2),
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.BR chown (2),
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.BR stat (2),
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.BR sticky (8)
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.SH STANDARDS
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.BR chmod
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is expected to conform to IEEE Std 1003.1-1988 (POSIX).
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.SH HISTORY
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The
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.BR fchmod
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function call
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appeared in 4.2BSD.
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