NAME
rm —
remove directory entries
SYNOPSIS
rm |
[-f | -i]
[-dPRrvWx] file
... |
DESCRIPTION
The
rm utility attempts to remove the non-directory type files
specified on the command line. If the permissions of the file do not permit
writing, and the standard input device is a terminal, the user is prompted (on
the standard error output) for confirmation.
The options are as follows:
-
-
- -d
- Attempt to remove directories as well as other types of
files.
-
-
- -f
- Attempt to remove the files without prompting for
confirmation, regardless of the file's permissions. If the file does not
exist, do not display a diagnostic message or modify the exit status to
reflect an error. The -f option overrides any previous
-i options.
-
-
- -i
- Request confirmation before attempting to remove each file,
regardless of the file's permissions, or whether or not the standard input
device is a terminal. The -i option overrides any
previous -f options.
-
-
- -P
- Overwrite regular files before deleting them. Files are
overwritten three times, first with the byte pattern 0xff, then 0x00, and
then with random data, before they are deleted. Some care is taken to
ensure that the data are actually written to disk, but this cannot be
guaranteed, even on traditional filesystems; on log-structured filesystems
or if any block-journaling scheme is in use, this option is completely
useless. If the file cannot be overwritten, it will not be removed.
-
-
- -R
- Attempt to remove the file hierarchy rooted in each file
argument. The -R option implies the -d
option. If the -i option is specified, the user is
prompted for confirmation before each directory's contents are processed
(as well as before the attempt is made to remove the directory). If the
user does not respond affirmatively, the file hierarchy rooted in that
directory is skipped.
-
-
- -r
- Equivalent to -R.
-
-
- -v
- Cause rm to be verbose, showing files as
they are processed.
-
-
- -W
- Attempts to undelete the named files. Currently, this
option can only be used to recover files covered by whiteouts.
-
-
- -x
- When removing a hierarchy, do not cross mount points.
The
rm utility removes symbolic links, not the files
referenced by the links.
It is an error to attempt to remove the files ``.'' and ``..''.
EXIT STATUS
The
rm utility exits 0 if all of the named files or file
hierarchies were removed, or if the
-f option was specified
and all of the existing files or file hierarchies were removed. If an error
occurs,
rm exits with a value >0.
EXAMPLES
rm uses
getopt(3) standard argument
processing. Removing filenames that begin with a dash (e.g.,
-file) in the current directory which might otherwise be
taken as option flags to
rm can be accomplished as follows:
rm -- -file
or
rm ./-file
COMPATIBILITY
The
rm utility differs from historical implementations in that
the
-f option only masks attempts to remove non-existent
files instead of masking a large variety of errors.
Also, historical
BSD implementations prompted on the
standard output, not the standard error output.
SEE ALSO
rmdir(1),
undelete(2),
unlink(2),
fts(3),
getopt(3),
symlink(7)
STANDARDS
The
rm utility is expected to be
IEEE Std
1003.2 (“POSIX.2”) compatible. The
-v and
-x options are extensions.
The
-P option attempts to conform to U.S. DoD 5220-22.M,
"National Industrial Security Program Operating Manual"
("NISPOM") as updated by Change 2 and the July 23, 2003
"Clearing & Sanitization Matrix". However, unlike earlier
revisions of NISPOM, the 2003 matrix imposes requirements which make it clear
that the standard does not and can not apply to the erasure of individual
files, in particular requirements relating to spare sector management for an
entire magnetic disk.
Because these requirements are not met,
the -P option does not conform to the
standard.
HISTORY
An
rm utility appeared in
Version 1
AT&T UNIX.
BUGS
The
-P option assumes that the underlying file system is a
fixed-block file system. FFS is a fixed-block file system, LFS is not. In
addition, only regular files are overwritten, other types of files are not.
Recent research indicates that as many as 35 overwrite passes with carefully
chosen data patterns may be necessary to actually prevent recovery of data
from a magnetic disk. Thus the
-P option is likely both
insufficient for its design purpose and far too costly for default operation.
However, it will at least prevent the recovery of data from FFS volumes with
fsdb(8).