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NAME
cp - copy files
SYNOPSIS
cp [-fip] source_file target_file
cp [-fip] source_file ... target
cp -R [-H | -L | -P][-fip] source_file ... target
cp -r [-H | -L | -P][-fip] source_file ... target
DESCRIPTION
The first synopsis form is denoted by two operands, neither of which are existing files of
type directory. The cp utility shall copy the contents of source_file (or, if source_file
is a file of type symbolic link, the contents of the file referenced by source_file) to
the destination path named by target_file.
The second synopsis form is denoted by two or more operands where the -R or -r options are
not specified and the first synopsis form is not applicable. It shall be an error if any
source_file is a file of type directory, if target does not exist, or if target is a file
of a type defined by the System Interfaces volume of IEEE Std 1003.1-2001, but is not a
file of type directory. The cp utility shall copy the contents of each source_file (or, if
source_file is a file of type symbolic link, the contents of the file referenced by
source_file) to the destination path named by the concatenation of target, a slash
character, and the last component of source_file.
The third and fourth synopsis forms are denoted by two or more operands where the -R or -r
options are specified. The cp utility shall copy each file in the file hierarchy rooted
in each source_file to a destination path named as follows:
* If target exists and is a file of type directory, the name of the corresponding
destination path for each file in the file hierarchy shall be the concatenation of
target, a slash character, and the pathname of the file relative to the directory
containing source_file.
* If target does not exist and two operands are specified, the name of the corresponding
destination path for source_file shall be target; the name of the corresponding
destination path for all other files in the file hierarchy shall be the concatenation
of target, a slash character, and the pathname of the file relative to source_file.
It shall be an error if target does not exist and more than two operands are specified, or
if target exists and is a file of a type defined by the System Interfaces volume of
IEEE Std 1003.1-2001, but is not a file of type directory.
In the following description, the term dest_file refers to the file named by the
destination path. The term source_file refers to the file that is being copied, whether
specified as an operand or a file in a file hierarchy rooted in a source_file operand. If
source_file is a file of type symbolic link:
* If neither the -R nor -r options were specified, cp shall take actions based on the
type and contents of the file referenced by the symbolic link, and not by the symbolic
link itself.
* If the -R option was specified:
* If none of the options -H, -L, nor -P were specified, it is unspecified which of -H,
-L, or -P will be used as a default.
* If the -H option was specified, cp shall take actions based on the type and contents
of the file referenced by any symbolic link specified as a source_file operand.
* If the -L option was specified, cp shall take actions based on the type and contents
of the file referenced by any symbolic link specified as a source_file operand or
any symbolic links encountered during traversal of a file hierarchy.
* If the -P option was specified, cp shall copy any symbolic link specified as a
source_file operand and any symbolic links encountered during traversal of a file
hierarchy, and shall not follow any symbolic links.
* If the -r option was specified, the behavior is implementation-defined.
For each source_file, the following steps shall be taken:
1. If source_file references the same file as dest_file, cp may write a diagnostic
message to standard error; it shall do nothing more with source_file and shall go on
to any remaining files.
2. If source_file is of type directory, the following steps shall be taken:
a. If neither the -R or -r options were specified, cp shall write a diagnostic
message to standard error, do nothing more with source_file, and go on to any
remaining files.
b. If source_file was not specified as an operand and source_file is dot or dot-dot,
cp shall do nothing more with source_file and go on to any remaining files.
c. If dest_file exists and it is a file type not specified by the System Interfaces
volume of IEEE Std 1003.1-2001, the behavior is implementation-defined.
d. If dest_file exists and it is not of type directory, cp shall write a diagnostic
message to standard error, do nothing more with source_file or any files below
source_file in the file hierarchy, and go on to any remaining files.
e. If the directory dest_file does not exist, it shall be created with file
permission bits set to the same value as those of source_file, modified by the
file creation mask of the user if the -p option was not specified, and then
bitwise-inclusively OR'ed with S_IRWXU. If dest_file cannot be created, cp shall
write a diagnostic message to standard error, do nothing more with source_file,
and go on to any remaining files. It is unspecified if cp attempts to copy files
in the file hierarchy rooted in source_file.
f. The files in the directory source_file shall be copied to the directory dest_file,
taking the four steps (1 to 4) listed here with the files as source_files.
g. If dest_file was created, its file permission bits shall be changed (if necessary)
to be the same as those of source_file, modified by the file creation mask of the
user if the -p option was not specified.
h. The cp utility shall do nothing more with source_file and go on to any remaining
files.
3. If source_file is of type regular file, the following steps shall be taken:
a. If dest_file exists, the following steps shall be taken:
i. If the -i option is in effect, the cp utility shall write a prompt to the
standard error and read a line from the standard input. If the response is
not affirmative, cp shall do nothing more with source_file and go on to any
remaining files.
ii. A file descriptor for dest_file shall be obtained by performing actions
equivalent to the open() function defined in the System Interfaces volume of
IEEE Std 1003.1-2001 called using dest_file as the path argument, and the
bitwise-inclusive OR of O_WRONLY and O_TRUNC as the oflag argument.
iii. If the attempt to obtain a file descriptor fails and the -f option is in
effect, cp shall attempt to remove the file by performing actions equivalent
to the unlink() function defined in the System Interfaces volume of
IEEE Std 1003.1-2001 called using dest_file as the path argument. If this
attempt succeeds, cp shall continue with step 3b.
b. If dest_file does not exist, a file descriptor shall be obtained by performing
actions equivalent to the open() function defined in the System Interfaces volume
of IEEE Std 1003.1-2001 called using dest_file as the path argument, and the
bitwise-inclusive OR of O_WRONLY and O_CREAT as the oflag argument. The file
permission bits of source_file shall be the mode argument.
c. If the attempt to obtain a file descriptor fails, cp shall write a diagnostic
message to standard error, do nothing more with source_file, and go on to any
remaining files.
d. The contents of source_file shall be written to the file descriptor. Any write
errors shall cause cp to write a diagnostic message to standard error and continue
to step 3e.
e. The file descriptor shall be closed.
f. The cp utility shall do nothing more with source_file. If a write error occurred
in step 3d, it is unspecified if cp continues with any remaining files. If no
write error occurred in step 3d, cp shall go on to any remaining files.
4. Otherwise, the following steps shall be taken:
a. If the -r option was specified, the behavior is implementation-defined.
b. If the -R option was specified, the following steps shall be taken:
i. The dest_file shall be created with the same file type as source_file.
ii. If source_file is a file of type FIFO, the file permission bits shall be the
same as those of source_file, modified by the file creation mask of the user
if the -p option was not specified. Otherwise, the permissions, owner ID, and
group ID of dest_file are implementation-defined.
If this creation fails for any reason, cp shall write a diagnostic message to
standard error, do nothing more with source_file, and go on to any remaining
files.
iii. If source_file is a file of type symbolic link, the pathname contained in
dest_file shall be the same as the pathname contained in source_file.
If this fails for any reason, cp shall write a diagnostic message to standard
error, do nothing more with source_file, and go on to any remaining files.
If the implementation provides additional or alternate access control mechanisms (see the
Base Definitions volume of IEEE Std 1003.1-2001, Section 4.4, File Access Permissions),
their effect on copies of files is implementation-defined.
OPTIONS
The cp 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:
-f If a file descriptor for a destination file cannot be obtained, as described in
step 3.a.ii., attempt to unlink the destination file and proceed.
-H Take actions based on the type and contents of the file referenced by any symbolic
link specified as a source_file operand.
-i Write a prompt to standard error before copying to any existing destination file.
If the response from the standard input is affirmative, the copy shall be
attempted; otherwise, it shall not.
-L Take actions based on the type and contents of the file referenced by any symbolic
link specified as a source_file operand or any symbolic links encountered during
traversal of a file hierarchy.
-P Take actions on any symbolic link specified as a source_file operand or any
symbolic link encountered during traversal of a file hierarchy.
-p Duplicate the following characteristics of each source file in the corresponding
destination file:
1. The time of last data modification and time of last access. If this duplication
fails for any reason, cp shall write a diagnostic message to standard error.
2. The user ID and group ID. If this duplication fails for any reason, it is
unspecified whether cp writes a diagnostic message to standard error.
3. The file permission bits and the S_ISUID and S_ISGID bits. Other,
implementation-defined, bits may be duplicated as well. If this duplication
fails for any reason, cp shall write a diagnostic message to standard error.
If the user ID or the group ID cannot be duplicated, the file permission bits S_ISUID and
S_ISGID shall be cleared. If these bits are present in the source file but are not
duplicated in the destination file, it is unspecified whether cp writes a diagnostic
message to standard error.
The order in which the preceding characteristics are duplicated is unspecified. The
dest_file shall not be deleted if these characteristics cannot be preserved.
-R Copy file hierarchies.
-r Copy file hierarchies. The treatment of special files is implementation-defined.
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:
source_file
A pathname of a file to be copied.
target_file
A pathname of an existing or nonexistent file, used for the output when a single
file is copied.
target A pathname of a directory to contain the copied 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 as operands may be of any file type.
ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of cp:
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) and 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 .
ASYNCHRONOUS EVENTS
Default.
STDOUT
Not used.
STDERR
A prompt shall be written to standard error under the conditions specified in the
DESCRIPTION section. The prompt shall contain the destination pathname, but its format is
otherwise unspecified. Otherwise, the standard error shall be used only for diagnostic
messages.
OUTPUT FILES
The output files may be of any type.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0 All files were copied successfully.
>0 An error occurred.
CONSEQUENCES OF ERRORS
If cp is prematurely terminated by a signal or error, files or file hierarchies may be
only partially copied and files and directories may have incorrect permissions or access
and modification times.
The following sections are informative.
APPLICATION USAGE
The difference between -R and -r is in the treatment by cp of file types other than
regular and directory. The original -r flag, for historic reasons, does not handle
special files any differently from regular files, but always reads the file and copies its
contents. This has obvious problems in the presence of special file types; for example,
character devices, FIFOs, and sockets. The -R option is intended to recreate the file
hierarchy and the -r option supports historical practice. It was anticipated that a future
version of this volume of IEEE Std 1003.1-2001 would deprecate the -r option, and for that
reason, there has been no attempt to fix its behavior with respect to FIFOs or other file
types where copying the file is clearly wrong. However, some implementations support -r
with the same abilities as the -R defined in this volume of IEEE Std 1003.1-2001. To
accommodate them as well as systems that do not, the differences between -r and -R are
implementation-defined. Implementations may make them identical. The -r option is marked
obsolescent.
The set-user-ID and set-group-ID bits are explicitly cleared when files are created. This
is to prevent users from creating programs that are set-user-ID or set-group-ID to them
when copying files or to make set-user-ID or set-group-ID files accessible to new groups
of users. For example, if a file is set-user-ID and the copy has a different group ID than
the source, a new group of users has execute permission to a set-user-ID program than did
previously. In particular, this is a problem for superusers copying users' trees.
EXAMPLES
None.
RATIONALE
The -i option exists on BSD systems, giving applications and users a way to avoid
accidentally removing files when copying. Although the 4.3 BSD version does not prompt if
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 on standard input.
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 using the
-i option relies on the system to provide the most suitable dialog directly with the user,
based on the behavior specified.
The -p option is historical practice on BSD systems, duplicating the time of last data
modification and time of last access. This volume of IEEE Std 1003.1-2001 extends it to
preserve the user and group IDs, as well as the file permissions. This requirement has
obvious problems in that the directories are almost certainly modified after being copied.
This volume of IEEE Std 1003.1-2001 requires that the modification times be preserved. The
statement that the order in which the characteristics are duplicated is unspecified is to
permit implementations to provide the maximum amount of security for the user.
Implementations should take into account the obvious security issues involved in setting
the owner, group, and mode in the wrong order or creating files with an owner, group, or
mode different from the final value.
It is unspecified whether cp writes diagnostic messages when the user and group IDs cannot
be set due to the widespread practice of users using -p to duplicate some portion of the
file characteristics, indifferent to the duplication of others. Historic implementations
only write diagnostic messages on errors other than [EPERM].
The -r option is historical practice on BSD and BSD-derived systems, copying file
hierarchies as opposed to single files. This functionality is used heavily in historical
applications, and its loss would significantly decrease consensus. The -R option was added
as a close synonym to the -r option, selected for consistency with all other options in
this volume of IEEE Std 1003.1-2001 that do recursive directory descent.
When a failure occurs during the copying of a file hierarchy, cp is required to attempt to
copy files that are on the same level in the hierarchy or above the file where the failure
occurred. It is unspecified if cp shall attempt to copy files below the file where the
failure occurred (which cannot succeed in any case).
Permissions, owners, and groups of created special file types have been deliberately left
as implementation-defined. This is to allow systems to satisfy special requirements (for
example, allowing users to create character special devices, but requiring them to be
owned by a certain group). In general, it is strongly suggested that the permissions,
owner, and group be the same as if the user had run the historical mknod, ln, or other
utility to create the file. It is also probable that additional privileges are required to
create block, character, or other implementation-defined special file types.
Additionally, the -p option explicitly requires that all set-user-ID and set-group-ID
permissions be discarded if any of the owner or group IDs cannot be set. This is to keep
users from unintentionally giving away special privilege when copying programs.
When creating regular files, historical versions of cp use the mode of the source file as
modified by the file mode creation mask. Other choices would have been to use the mode of
the source file unmodified by the creation mask or to use the same mode as would be given
to a new file created by the user (plus the execution bits of the source file) and then
modify it by the file mode creation mask. In the absence of any strong reason to change
historic practice, it was in large part retained.
When creating directories, historical versions of cp use the mode of the source directory,
plus read, write, and search bits for the owner, as modified by the file mode creation
mask. This is done so that cp can copy trees where the user has read permission, but the
owner does not. A side effect is that if the file creation mask denies the owner
permissions, cp fails. Also, once the copy is done, historical versions of cp set the
permissions on the created directory to be the same as the source directory, unmodified by
the file creation mask.
This behavior has been modified so that cp is always able to create the contents of the
directory, regardless of the file creation mask. After the copy is done, the permissions
are set to be the same as the source directory, as modified by the file creation mask.
This latter change from historical behavior is to prevent users from accidentally creating
directories with permissions beyond those they would normally set and for consistency with
the behavior of cp in creating files.
It is not a requirement that cp detect attempts to copy a file to itself; however,
implementations are strongly encouraged to do so. Historical implementations have detected
the attempt in most cases.
There are two methods of copying subtrees in this volume of IEEE Std 1003.1-2001. The
other method is described as part of the pax utility (see pax ). Both methods are
historical practice. The cp utility provides a simpler, more intuitive interface, while
pax offers a finer granularity of control. Each provides additional functionality to the
other; in particular, pax maintains the hard-link structure of the hierarchy, while cp
does not. It is the intention of the standard developers that the results be similar
(using appropriate option combinations in both utilities). The results are not required to
be identical; there seemed insufficient gain to applications to balance the difficulty of
implementations having to guarantee that the results would be exactly identical.
The wording allowing cp to copy a directory to implementation-defined file types not
specified by the System Interfaces volume of IEEE Std 1003.1-2001 is provided so that
implementations supporting symbolic links are not required to prohibit copying directories
to symbolic links. Other extensions to the System Interfaces volume of
IEEE Std 1003.1-2001 file types may need to use this loophole as well.
FUTURE DIRECTIONS
The -r option may be removed; use -R instead.
SEE ALSO
mv , find , ln , pax , the System Interfaces volume of IEEE Std 1003.1-2001, open(),
unlink()
COPYRIGHT
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 .