In the first synopsis form, the mv utility shall move the file
named by the source_file operand to the destination
specified by the target_file. This first synopsis form is assumed
when the final operand does not name an existing directory
and is not a symbolic link referring to an existing directory.
In the second synopsis form, mv shall move each file named by
a source_file operand to a destination file in the
existing directory named by the target_dir operand, or referenced
if target_dir is a symbolic link referring to an
existing directory. The destination path for each source_file
shall be the concatenation of the target directory, a single
slash character, and the last pathname component of the source_file.
This second form is assumed when the final operand
names an existing directory.
If any operand specifies an existing file of a type not specified
by the System Interfaces volume of
IEEE Std 1003.1-2001, the behavior is implementation-defined.
For each source_file the following steps shall be taken:
1.
If the destination path exists, the -f option is not specified,
and either of the following conditions is true:
a.
The permissions of the destination path do not permit writing and
the standard input is a terminal.
b.
The -i option is specified.
the mv utility shall write a prompt to standard error and read
a line from standard input. If the response is not
affirmative, mv shall do nothing more with the current source_file
and go on to any remaining
source_files.
2.
The mv utility shall perform actions equivalent to the rename()
function
defined in the System Interfaces volume of IEEE Std 1003.1-2001,
called with the following arguments:
a.
The source_file operand is used as the old argument.
b.
The destination path is used as the new argument.
If this succeeds, mv shall do nothing more with the current
source_file and go on to any remaining
source_files. If this fails for any reasons other than those
described for the errno [EXDEV] in the System Interfaces
volume of IEEE Std 1003.1-2001, mv shall write a diagnostic
message to standard error, do nothing more with the
current source_file, and go on to any remaining source_files.
3.
If the destination path exists, and it is a file of type directory
and source_file is not a file of type directory, or it
is a file not of type directory and source_file is a file of
type directory, mv shall write a diagnostic message to
standard error, do nothing more with the current source_file,
and go on to any remaining source_files.
4.
If the destination path exists, mv shall attempt to remove it.
If this fails for any reason, mv shall write a
diagnostic message to standard error, do nothing more with the current
source_file, and go on to any remaining
source_files.
5.
The file hierarchy rooted in source_file shall be duplicated
as a file hierarchy rooted in the destination path. If
source_file or any of the files below it in the hierarchy are
symbolic links, the links themselves shall be duplicated,
including their contents, rather than any files to which they refer.
The following characteristics of each file in the file
hierarchy shall be duplicated:
*
The time of last data modification and time of last access
*
The user ID and group ID
*
The file mode
If the user ID, group ID, or file mode of a regular file cannot be
duplicated, the file mode bits S_ISUID and S_ISGID shall not
be duplicated.
When files are duplicated to another file system, the implementation
may require that the process invoking mv has read
access to each file being duplicated.
If the duplication of the file hierarchy fails for any reason, mv
shall write a diagnostic message to standard error, do
nothing more with the current source_file, and go on to any
remaining source_files.
If the duplication of the file characteristics fails for any reason,
mv shall write a diagnostic message to standard
error, but this failure shall not cause mv to modify its exit
status.
6.
The file hierarchy rooted in source_file shall be removed. If
this fails for any reason, mv shall write a
diagnostic message to the standard error, do nothing more with the
current source_file, and go on to any remaining
source_files.
The standard input shall be used to read an input line in response
to each prompt specified in the STDERR section. Otherwise,
the standard input shall not be used.
The following environment variables shall affect the execution of
mv:
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_COLLATE
Determine the locale for the behavior of ranges, equivalence classes,
and multi-character collating elements used in the extended
regular expression defined for the yesexpr locale keyword in
the LC_MESSAGES category.
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 and input files), the
behavior of character classes used in the extended regular
expression defined for the yesexpr locale keyword in the LC_MESSAGES
category.
LC_MESSAGES
Determine the locale for the processing of affirmative responses 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
.
Prompts shall be written to the standard error under the conditions
specified in the DESCRIPTION section. The prompts shall
contain the destination pathname, but their format is otherwise unspecified.
Otherwise, the standard error shall be used only for
diagnostic messages.
If the copying or removal of source_file is prematurely terminated
by a signal or error, mv may leave a partial
copy of source_file at the source or destination. The mv
utility shall not modify both source_file and the
destination path simultaneously; termination at any point shall leave
either source_file or the destination path
complete.
Some implementations mark for update the st_ctime field of renamed
files and some do not. Applications which make use of
the st_ctime field may behave differently with respect to renamed
files unless they are designed to allow for either
behavior.
If the current directory contains only files a (of any type
defined by the System Interfaces volume of
IEEE Std 1003.1-2001), b (also of any type), and a directory
c:
mv a b c
mv c d
results with the original files a and b residing in the
directory d in the current directory.
Early proposals diverged from the SVID and BSD historical practice
in that they required that when the destination path exists,
the -f option is not specified, and input is not a terminal,
mv fails. This was done for compatibility with cp. The
current text returns to historical practice. It should be noted that
this is consistent
with the rename() function defined in the System Interfaces
volume of
IEEE Std 1003.1-2001, which does not require write permission on
the target.
For absolute clarity, paragraph (1), describing the behavior of mv
when prompting for confirmation, should be interpreted
in the following manner:
if (exists AND (NOT f_option) AND
((not_writable AND input_is_terminal) OR i_option))
The -i option exists on BSD systems, giving applications and
users a way to avoid accidentally unlinking files when
moving others. When the standard input is not a terminal, the 4.3
BSD mv deletes all existing destination paths without
prompting, even when -i is specified; this is inconsistent with
the behavior of the 4.3 BSD cp utility, which always generates
an error when the file is unwritable and the standard input is
not a terminal. The standard developers decided that use of -i
is a request for interaction, so when the destination path
exists, the utility takes instructions from whatever responds to standard
input.
The rename() function is able to move directories within the
same file system.
Some historical versions of mv have been able to move directories,
but not to a different file system. The standard
developers considered that this was an annoying inconsistency, so
this volume of IEEE Std 1003.1-2001 requires
directories to be able to be moved even across file systems. There
is no -R option to confirm that moving a directory is
actually intended, since such an option was not required for moving
directories in historical practice. Requiring the application
to specify it sometimes, depending on the destination, seemed just
as inconsistent. The semantics of the rename() function were
preserved as much as possible. For example, mv is not permitted
to "rename" files to or from directories, even though they might be
empty and removable.
Historic implementations of mv did not exit with a non-zero
exit status if they were unable to duplicate any file
characteristics when moving a file across file systems, nor did they
write a diagnostic message for the user. The former behavior
has been preserved to prevent scripts from breaking; a diagnostic
message is now required, however, so that users are alerted that
the file characteristics have changed.
The exact format of the interactive prompts is unspecified. Only the
general nature of the contents of prompts are specified
because implementations may desire more descriptive prompts than those
used on historical implementations. Therefore, an
application not using the -f option or using the -i option
relies on the system to provide the most suitable dialog
directly with the user, based on the behavior specified.
When mv is dealing with a single file system and source_file
is a symbolic link, the link itself is moved as a
consequence of the dependence on the rename() functionality,
per the DESCRIPTION.
Across file systems, this has to be made explicit.
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 .
IEEE/The Open Group
MV (P)
2003
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