Originální popis anglicky:
chown - change the file ownership
Návod, kniha: POSIX Programmer's Manual
chown [-hR]
owner[:group] file ...
chown -R
[-H | -L | -P ]
owner
[:group]
file ...
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 arguments:
- 1.
- The file operand shall be used as the path
argument.
- 2.
- The user ID indicated by the owner portion of the
first operand shall be used as the owner argument.
- 3.
- 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 completion; the set-user-ID and set-group-ID bits of other file
types may be cleared.
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 implementation:
- -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 operand 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
specified) of the symbolic link if the system supports 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 specified) 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.
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 portion 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 modified.
Not used.
None.
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, Internationalization
Variables for the precedence of internationalization 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 messages written to standard error.
- NLSPATH
- Determine the location of message catalogs for the
processing of LC_MESSAGES .
Default.
Not used.
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
- 0
- The utility executed successfully and all requested changes
were made.
- >0
- An error occurred.
Default.
The following sections are informative.
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.
None.
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 practice 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 interactions 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 specified by the Base
Definitions volume of IEEE Std 1003.1-2001, login names consist
of characters in the portable filename character set). The colon character was
chosen as the replacement for the period character because it would never be
allowed as a character in a user name or group name on historical
implementations.
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.
None.
chmod ,
chgrp , the System Interfaces volume of
IEEE Std 1003.1-2001,
chown()
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute 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
.
