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CHOWN(1P)                  POSIX Programmer's Manual                 CHOWN(1P)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may dif-
       fer (consult the corresponding Linux manual page for details of Linux behavior), or the interface  may  not  be
       implemented on Linux.

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 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.

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 implementation:

       -h     If the system supports user IDs for symbolic links, for each file operand that names a file of type sym-
              bolic  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 sup-
              port 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  refer-
              enced 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.

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.  Simi-
              larly, 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.


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, Internationalization Variables for the prece-
              dence 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 exam-
              ple, 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  writ-
              ten 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 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% perfor-
          mance 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 charac-
       ter 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 hier-
       archy, 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, Stan-
       dard  for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifica-
       tions 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 Stan-
       dard, 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 .



IEEE/The Open Group                  2003                            CHOWN(1P)