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chown(P) chown(P)
NAME
chown - change the file ownership
SYNOPSIS
chown [-hR] owner[:group] file ...
chown -R [-H | -L | -P ] owner[:group] file ...
DESCRIPTION
The chown utility shall set the user ID of the file
named by each file operand to the user ID specified by
the owner operand.
For each file operand, or, if the -R option is used,
each file encountered while walking the directory trees
specified by the file operands, the chown utility shall
perform actions equivalent to the chown() function
defined in the System Interfaces volume of
IEEE Std 1003.1-2001, called with the following argu-
ments:
The file operand shall be used as the path argument.
The user ID indicated by the owner portion of the first
operand shall be used as the owner argument.
If the group portion of the first operand is given, the
group ID indicated by it shall be used as the group
argument; otherwise, the group ownership shall not be
changed.
Unless chown is invoked by a process with appropriate
privileges, the set-user-ID and set-group-ID bits of a
regular file shall be cleared upon successful comple-
tion; the set-user-ID and set-group-ID bits of other
file types may be cleared.
OPTIONS
The chown utility shall conform to the Base Definitions
volume of IEEE Std 1003.1-2001, Section 12.2, Utility
Syntax Guidelines.
The following options shall be supported by the imple-
mentation:
-h If the system supports user IDs for symbolic
links, for each file operand that names a file of
type symbolic link, chown shall attempt to set
the user ID of the symbolic link. If the system
supports group IDs for symbolic links, and a
group ID was specified, for each file operand
that names a file of type symbolic link, chown
shall attempt to set the group ID of the symbolic
link. If the system does not support user or
group IDs for symbolic links, for each file oper-
and that names a file of type symbolic link,
chown shall do nothing more with the current file
and shall go on to any remaining files.
-H If the -R option is specified and a symbolic link
referencing a file of type directory is specified
on the command line, chown shall change the user
ID (and group ID, if specified) of the directory
referenced by the symbolic link and all files in
the file hierarchy below it.
-L If the -R option is specified and a symbolic link
referencing a file of type directory is specified
on the command line or encountered during the
traversal of a file hierarchy, chown shall change
the user ID (and group ID, if specified) of the
directory referenced by the symbolic link and all
files in the file hierarchy below it.
-P If the -R option is specified and a symbolic link
is specified on the command line or encountered
during the traversal of a file hierarchy, chown
shall change the owner ID (and group ID, if spec-
ified) of the symbolic link if the system sup-
ports this operation. The chown utility shall not
follow the symbolic link to any other part of the
file hierarchy.
-R Recursively change file user and group IDs. For
each file operand that names a directory, chown
shall change the user ID (and group ID, if speci-
fied) of the directory and all files in the file
hierarchy below it. Unless a -H, -L, or -P option
is specified, it is unspecified which of these
options will be used as the default.
Specifying more than one of the mutually-exclusive
options -H, -L, and -P shall not be considered an error.
The last option specified shall determine the behavior
of the utility.
OPERANDS
The following operands shall be supported:
owner[:group]
A user ID and optional group ID to be assigned to
file. The owner portion of this operand shall be
a user name from the user database or a numeric
user ID. Either specifies a user ID which shall
be given to each file named by one of the file
operands. If a numeric owner operand exists in
the user database as a user name, the user ID
number associated with that user name shall be
used as the user ID. Similarly, if the group por-
tion of this operand is present, it shall be a
group name from the group database or a numeric
group ID. Either specifies a group ID which shall
be given to each file. If a numeric group operand
exists in the group database as a group name, the
group ID number associated with that group name
shall be used as the group ID.
file A pathname of a file whose user ID is to be modi-
fied.
STDIN
Not used.
INPUT FILES
None.
ENVIRONMENT VARIABLES
The following environment variables shall affect the
execution of chown:
LANG Provide a default value for the
internationalization variables that are unset or
null. (See the Base Definitions volume of
IEEE Std 1003.1-2001, Section 8.2, International-
ization Variables for the precedence of interna-
tionalization variables used to determine the
values of locale categories.)
LC_ALL If set to a non-empty string value, override the
values of all the other internationalization
variables.
LC_CTYPE
Determine the locale for the interpretation of
sequences of bytes of text data as characters
(for example, single-byte as opposed to multi-
byte characters in arguments).
LC_MESSAGES
Determine the locale that should be used to
affect the format and contents of diagnostic mes-
sages written to standard error.
NLSPATH
Determine the location of message catalogs for
the processing of LC_MESSAGES .
ASYNCHRONOUS EVENTS
Default.
STDOUT
Not used.
STDERR
The standard error shall be used only for diagnostic
messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0 The utility executed successfully and all
requested changes were made.
>0 An error occurred.
CONSEQUENCES OF ERRORS
Default.
The following sections are informative.
APPLICATION USAGE
Only the owner of a file or the user with appropriate
privileges may change the owner or group of a file.
Some implementations restrict the use of chown to a user
with appropriate privileges.
EXAMPLES
None.
RATIONALE
The System V and BSD versions use different exit status
codes. Some implementations used the exit status as a
count of the number of errors that occurred; this prac-
tice is unworkable since it can overflow the range of
valid exit status values. These are masked by specifying
only 0 and >0 as exit values.
The functionality of chown is described substantially
through references to functions in the System Interfaces
volume of IEEE Std 1003.1-2001. In this way, there is no
duplication of effort required for describing the inter-
actions of permissions, multiple groups, and so on.
The 4.3 BSD method of specifying both owner and group
was included in this volume of IEEE Std 1003.1-2001
because:
There are cases where the desired end condition
could not be achieved using the chgrp and chown
(that only changed the user ID) utilities. (If
the current owner is not a member of the desired
group and the desired owner is not a member of
the current group, the chown() function could
fail unless both owner and group are changed at
the same time.)
Even if they could be changed independently, in
cases where both are being changed, there is a
100% performance penalty caused by being forced
to invoke both utilities.
The BSD syntax user[. group] was changed to user[:
group] in this volume of IEEE Std 1003.1-2001 because
the period is a valid character in login names (as spec-
ified by the Base Definitions volume of
IEEE Std 1003.1-2001, login names consist of characters
in the portable filename character set). The colon char-
acter was chosen as the replacement for the period char-
acter because it would never be allowed as a character
in a user name or group name on historical implementa-
tions.
The -R option is considered by some observers as an
undesirable departure from the historical UNIX system
tools approach; since a tool, find, already exists to
recurse over directories, there seemed to be no good
reason to require other tools to have to duplicate that
functionality. However, the -R option was deemed an
important user convenience, is far more efficient than
forking a separate process for each element of the
directory hierarchy, and is in widespread historical
use.
FUTURE DIRECTIONS
None.
SEE ALSO
chmod , chgrp , the System Interfaces volume of
IEEE Std 1003.1-2001, chown()
COPYRIGHT
Portions of this text are reprinted and reproduced in
electronic form from IEEE Std 1003.1, 2003 Edition,
Standard for Information Technology -- Portable Operat-
ing System Interface (POSIX), The Open Group Base Speci-
fications Issue 6, Copyright (C) 2001-2003 by the Insti-
tute of Electrical and Electronics Engineers, Inc and
The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group
Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be
obtained online at
http://www.opengroup.org/unix/online.html .
POSIX 2003 chown(P)
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