Ubuntu Manpage: This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

Provided by: manpages-posix_2017a-2_all

PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (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 [-h] 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 POSIX.1‐2017, 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 POSIX.1‐2017, Section 12.2, Utility
Syntax Guidelines.

The following options shall be supported by the implementation:

-h 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 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.

-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. 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. 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.

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 POSIX.1‐2017, 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.

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 POSIX.1‐2017. 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  POSIX.1‐2017
       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 POSIX.1‐2017 because the
       <period> is a  valid  character  in  login  names  (as  specified  by  the  Base  Definitions  volume  of
       POSIX.1‐2017,  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.

FUTURE DIRECTIONS

       None.

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       Any  typographical  or formatting errors that appear in this page are most likely to have been introduced
       during  the  conversion  of  the  source  files  to  man  page  format.  To  report  such   errors,   see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .