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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
mv — move files
SYNOPSIS
mv [-if] source_file target_file
mv [-if] source_file... target_dir
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.
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.
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.
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.
INPUT FILES
The input files specified by each source_file operand can be of any file type.
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.
ASYNCHRONOUS EVENTS
Default.
STDOUT
Not used.
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.
OUTPUT FILES
The output files may be of any file type.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0 All input files were moved successfully.
>0 An error occurred.
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.
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).
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.
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.
FUTURE DIRECTIONS
None.
SEE ALSO
cp, ln
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()
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 .