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CP(1P) POSIX Programmer's Manual CP(1P)
PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (con-
sult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on
Linux.
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 ref-
erenced 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 ref-
erenced 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 hier-
archy.
* 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 con-
tinue 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 argu-
ment, 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 noth-
ing 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 permis-
sions, 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 Guide-
lines.
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 stan-
dard 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 tra-
versal 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 dupli-
cated 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. Other-
wise, 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 international-
ization 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 con-
tents 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 histori-
cal 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 obsoles-
cent.
The set-user-ID and set-group-ID bits are explicitly cleared when files are created. This is to prevent users from creat-
ing 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 copy-
ing. 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 speci-
fied because implementations may desire more descriptive prompts than those used on historical implementations. There-
fore, 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 permis-
sions. 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 oth-
ers. 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 proba-
ble 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 copy-
ing programs.
When creating regular files, historical versions of cp use the mode of the source file as modified by the file mode cre-
ation 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 directo-
ries 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 encour-
aged 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 par-
ticular, 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, Copy-
right (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.open-
group.org/unix/online.html .
IEEE/The Open Group 2003 CP(1P)
