Originální popis anglicky:
rm - remove directory entries
Návod, kniha: POSIX Programmer's Manual
rm [-fiRr] file...
The
rm utility shall remove the directory entry specified by each
file argument.
If either of the files dot or dot-dot are specified as the basename portion of
an operand (that is, the final pathname component),
rm shall write a
diagnostic message to standard error and do nothing more with such operands.
For each
file the following steps shall be taken:
- 1.
- If the file does not exist:
- a.
- If the -f option is not specified, rm shall
write a diagnostic message to standard error.
- b.
- Go on to any remaining files.
- 2.
- If file is of type directory, the following steps
shall be taken:
- a.
- If neither the -R option nor the -r option is
specified, rm shall write a diagnostic message to standard error,
do nothing more with file, and go on to any remaining files.
- b.
- If the -f option is not specified, and either the
permissions of file do not permit writing and the standard input is
a terminal or the -i option is specified, rm shall write a
prompt to standard error and read a line from the standard input. If the
response is not affirmative, rm shall do nothing more with the
current file and go on to any remaining files.
- c.
- For each entry contained in file, other than dot or
dot-dot, the four steps listed here (1 to 4) shall be taken with the entry
as if it were a file operand. The rm utility shall not
traverse directories by following symbolic links into other parts of the
hierarchy, but shall remove the links themselves.
- d.
- If the -i option is specified, rm shall write
a prompt to standard error and read a line from the standard input. If the
response is not affirmative, rm shall do nothing more with the
current file, and go on to any remaining files.
- 3.
- If file is not of type directory, the -f
option is not specified, and either the permissions of file do not
permit writing and the standard input is a terminal or the -i
option is specified, rm shall write a prompt to the standard error
and read a line from the standard input. If the response is not
affirmative, rm shall do nothing more with the current file and go
on to any remaining files.
- 4.
- If the current file is a directory, rm shall perform
actions equivalent to the rmdir() function defined in the System
Interfaces volume of IEEE Std 1003.1-2001 called with a
pathname of the current file used as the path argument. If the
current file is not a directory, rm shall perform actions
equivalent to the unlink() function defined in the System
Interfaces volume of IEEE Std 1003.1-2001 called with a
pathname of the current file used as the path argument.
If this fails for any reason,
rm shall write a diagnostic message to
standard error, do nothing more with the current file, and go on to any
remaining files.
The
rm utility shall be able to descend to arbitrary depths in a file
hierarchy, and shall not fail due to path length limitations (unless an
operand specified by the user exceeds system limitations).
The
rm 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
- Do not prompt for confirmation. Do not write diagnostic
messages or modify the exit status in the case of nonexistent operands.
Any previous occurrences of the -i option shall be ignored.
- -i
- Prompt for confirmation as described previously. Any
previous occurrences of the -f option shall be ignored.
- -R
- Remove file hierarchies. See the DESCRIPTION.
- -r
- Equivalent to -R.
The following operand shall be supported:
- file
- A pathname of a directory entry to be removed.
The standard input shall be used to read an input line in response to each
prompt specified in the STDOUT section. Otherwise, the standard input shall
not be used.
None.
The following environment variables shall affect the execution of
rm:
- 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 the behavior of character classes
within regular expressions 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 .
Default.
Not used.
Prompts shall be written to standard error under the conditions specified in the
DESCRIPTION and OPTIONS sections. The prompts shall contain the
file
pathname, but their format is otherwise unspecified. The standard error also
shall be used for diagnostic messages.
None.
None.
The following exit values shall be returned:
- 0
- All of the named directory entries for which rm
performed actions equivalent to the rmdir() or unlink()
functions were removed.
- >0
- An error occurred.
Default.
The following sections are informative.
The
rm utility is forbidden to remove the names dot and dot-dot in order
to avoid the consequences of inadvertently doing something like:
Some implementations do not permit the removal of the last link to an executable
binary file that is being executed; see the [EBUSY] error in the
unlink() function defined in the System Interfaces volume of
IEEE Std 1003.1-2001. Thus, the
rm utility can fail to
remove such files.
The
-i option causes
rm to prompt and read the standard input even
if the standard input is not a terminal, but in the absence of
-i the
mode prompting is not done when the standard input is not a terminal.
- 1.
- The following command:
removes the directory entries:
a.out and
core.
- 2.
- The following command:
removes the directory
junk and all its contents, without prompting.
For absolute clarity, paragraphs (2b) and (3) in the DESCRIPTION of
rm
describing the behavior when prompting for confirmation, should be interpreted
in the following manner:
if ((NOT f_option) AND
((not_writable AND input_is_terminal) OR i_option))
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.
The
-r option is historical practice on all known systems. The synonym
-R option is provided for consistency with the other utilities in this
volume of IEEE Std 1003.1-2001 that provide options requesting
recursive descent through the file hierarchy.
The behavior of the
-f option in historical versions of
rm is
inconsistent. In general, along with "forcing" the unlink without
prompting for permission, it always causes diagnostic messages to be
suppressed and the exit status to be unmodified for nonexistent operands and
files that cannot be unlinked. In some versions, however, the
-f option
suppresses usage messages and system errors as well. Suppressing such messages
is not a service to either shell scripts or users.
It is less clear that error messages regarding files that cannot be unlinked
(removed) should be suppressed. Although this is historical practice, this
volume of IEEE Std 1003.1-2001 does not permit the
-f
option to suppress such messages.
When given the
-r and
-i options, historical versions of
rm
prompt the user twice for each directory, once before removing its contents
and once before actually attempting to delete the directory entry that names
it. This allows the user to "prune" the file hierarchy walk.
Historical versions of
rm were inconsistent in that some did not do the
former prompt for directories named on the command line and others had obscure
prompting behavior when the
-i option was specified and the permissions
of the file did not permit writing. The POSIX Shell and Utilities
rm
differs little from historic practice, but does require that prompts be
consistent. Historical versions of
rm were also inconsistent in that
prompts were done to both standard output and standard error. This volume of
IEEE Std 1003.1-2001 requires that prompts be done to standard
error, for consistency with
cp and
mv, and to allow historical
extensions to
rm that provide an option to list deleted files on
standard output.
The
rm utility is required to descend to arbitrary depths so that any
file hierarchy may be deleted. This means, for example, that the
rm
utility cannot run out of file descriptors during its descent (that is, if the
number of file descriptors is limited,
rm cannot be implemented in the
historical fashion where one file descriptor is used per directory level).
Also,
rm is not permitted to fail because of path length restrictions,
unless an operand specified by the user is longer than {PATH_MAX}.
The
rm utility removes symbolic links themselves, not the files they
refer to, as a consequence of the dependence on the
unlink()
functionality, per the DESCRIPTION. When removing hierarchies with
-r
or
-R, the prohibition on following symbolic links has to be made
explicit.
None.
rmdir() , the System Interfaces volume of
IEEE Std 1003.1-2001,
remove(),
rmdir(),
unlink()
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
.
