переместить файлы (move files)
Пролог (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.
Имя (Name)
mv — move files
Синопсис (Synopsis)
mv [-if] source_file target_file
mv [-if] source_file... target_dir
Описание (Description)
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 this case,
if source_file names a non-directory file and target_file ends
with a trailing <slash> character, mv shall treat this as an
error and no source_file operands will be processed.
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
if the target did not end in a <slash>, 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 POSIX.1‐2017, 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. If the source_file operand and destination path resolve to
either the same existing directory entry or different
directory entries for the same existing file, then the
destination path shall not be removed, and one of the
following shall occur:
a. No change is made to source_file, no error occurs, and no
diagnostic is issued.
b. No change is made to source_file, a diagnostic is issued
to standard error identifying the two names, and the exit
status is affected.
c. If the source_file operand and destination path name
distinct directory entries, then the source_file operand
is removed, no error occurs, and no diagnostic is issued.
The mv utility shall do nothing more with the current
source_file, and go on to any remaining source_files.
3. The mv utility shall perform actions equivalent to the
rename() function defined in the System Interfaces volume of
POSIX.1‐2017, 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
POSIX.1‐2017, 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, 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. If the destination
path exists and was created by a previous step, it is
unspecified whether this will treated as an error or the
destination path will be overwritten.
5. 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.
6. 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 files being duplicated to another file system have hard
links to other files, it is unspecified whether the files
copied to the new file system have the hard links preserved
or separate copies are created for the linked files.
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.
7. 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.
Параметры (Options)
The mv utility shall conform to the Base Definitions volume of
POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
The following options shall be supported:
-f Do not prompt for confirmation if the destination path
exists. Any previous occurrence of the -i option is
ignored.
-i Prompt for confirmation if the destination path exists.
Any previous occurrence of the -f option is ignored.
Specifying more than one of the -f or -i options shall not be
considered an error. The last option specified shall determine
the behavior of mv.
Операнды (Operands)
The following operands shall be supported:
source_file
A pathname of a file or directory to be moved.
target_file
A new pathname for the file or directory being moved.
target_dir
A pathname of an existing directory into which to move
the input files.
Стандартный ввод (Stdin)
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.
Входные файлы (Input files)
The input files specified by each source_file operand can be of
any file type.
Переменные окружения (Environment variables)
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 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_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 used to process affirmative
responses, and the locale used to affect the format and
contents of diagnostic messages and prompts written to
standard error.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
Асинхронные события (Asynchronous events)
Default.
Стандартный вывод (Stdout)
Not used.
Стандартный вывод сообщений (Stderr)
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.
Выходные файлы (Output files)
The output files may be of any file type.
Расширенное описание (Extended description)
None.
Статус выхода (Exit)
The following exit values shall be returned:
0 All input files were moved successfully.
>0 An error occurred.
Последствия ошибок (Consequences of errors)
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.
The following sections are informative.
Использование в приложениях (Application usage)
Some implementations mark for update the last file status change
timestamp of renamed files and some do not. Applications which
make use of the last file status change timestamp may behave
differently with respect to renamed files unless they are
designed to allow for either behavior.
The specification ensures that mv a a will not alter the contents
of file a, and allows the implementation to issue an error that a
file cannot be moved onto itself. Likewise, when a and b are hard
links to the same file, mv a b will not alter b, but if a
diagnostic is not issued, then it is unspecified whether a is
left untouched (as it would be by the rename() function) or
unlinked (reducing the link count of b).
Примеры (Examples)
If the current directory contains only files a (of any type
defined by the System Interfaces volume of POSIX.1‐2017), 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.
Обоснование (Rationale)
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 POSIX.1‐2017, 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 POSIX.1‐2017 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.
Будущие направления (Future directions)
None.
Смотри также (See also)
cp(1p), ln(1p)
The Base Definitions volume of POSIX.1‐2017, Chapter 8,
Environment Variables, Section 12.2, Utility Syntax Guidelines
The System Interfaces volume of POSIX.1‐2017, rename(3p)
