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.
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.
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
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
.
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.
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 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.
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.
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
CP (P)
2003
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