Ubuntu Manpage: cp - copy files

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.

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 .