# tar
> Archiving utility.
> Often combined with a compression method, such as gzip or bzip2.
> More information: <https://www.gnu.org/software/tar>.
- [c]reate an archive and write it to a [f]ile:
`tar cf {{path/to/target.tar}} {{path/to/file1 path/to/file2 ...}}`
- [c]reate a g[z]ipped archive and write it to a [f]ile:
`tar czf {{path/to/target.tar.gz}} {{path/to/file1 path/to/file2 ...}}`
- [c]reate a g[z]ipped archive from a directory using relative paths:
`tar czf {{path/to/target.tar.gz}} --directory={{path/to/directory}} .`
- E[x]tract a (compressed) archive [f]ile into the current directory [v]erbosely:
`tar xvf {{path/to/source.tar[.gz|.bz2|.xz]}}`
- E[x]tract a (compressed) archive [f]ile into the target directory:
`tar xf {{path/to/source.tar[.gz|.bz2|.xz]}} --directory={{path/to/directory}}`
- [c]reate a compressed archive and write it to a [f]ile,
using [a]rchive suffix to determine the compression program:
`tar caf {{path/to/target.tar.xz}} {{path/to/file1 path/to/file2 ...}}`
- Lis[t] the contents of a tar [f]ile [v]erbosely:
`tar tvf {{path/to/source.tar}}`
- E[x]tract files matching a pattern from an archive [f]ile:
`tar xf {{path/to/source.tar}} --wildcards "{{*.html}}"`{tldr}
Quick Documentation in the R Console
James Otto (Alcon Laboratories)
David Kahle (Baylor University)
8/8/2023
Modern Software Documentation
Docs for Developers (Bhatti et al. (2021))
- User base
- User needs
- Example selection
- “Explanatory” and “executable”
- Explained, concise, clear, extensible, and trustworthy
Example Forward Documentation
- Analysis of StackOverflow answers (Nasehi et al. (2012)) identified nine traits of “recognized” answers:
- Concise code samples
- Inline documentation
- Multiple solutions
- Links to extra resources
tldr-pages
tldr-pages
tldr-pages
> man tar
TAR(1) GNU TAR Manual TAR(1)
NAME
tar - an archiving utility
SYNOPSIS
Traditional usage
tar {A|c|d|r|t|u|x}[GnSkUWOmpsMBiajJzZhPlRvwo] [ARG...]
UNIX-style usage
tar -A [OPTIONS] -f ARCHIVE ARCHIVE
tar -c [-f ARCHIVE] [OPTIONS] [FILE...]
tar -d [-f ARCHIVE] [OPTIONS] [FILE...]
tar -r [-f ARCHIVE] [OPTIONS] [FILE...]
tar -t [-f ARCHIVE] [OPTIONS] [MEMBER...]
tar -u [-f ARCHIVE] [OPTIONS] [FILE...]
tar -x [-f ARCHIVE] [OPTIONS] [MEMBER...]
GNU-style usage
tar {--catenate|--concatenate} [OPTIONS] --file ARCHIVE ARCHIVE
tar --create [--file ARCHIVE] [OPTIONS] [FILE...]
tar {--diff|--compare} [--file ARCHIVE] [OPTIONS] [FILE...]
tar --delete [--file ARCHIVE] [OPTIONS] [MEMBER...]
tar --append [--file ARCHIVE] [OPTIONS] [FILE...]
tar --list [--file ARCHIVE] [OPTIONS] [MEMBER...]
tar --test-label [--file ARCHIVE] [OPTIONS] [LABEL...]
tar --update [--file ARCHIVE] [OPTIONS] [FILE...]
tar {--extract|--get} [--file ARCHIVE] [OPTIONS] [MEMBER...]
NOTE
This manpage is a short description of GNU tar. For a detailed
discussion, including examples and usage recommendations, refer
to the GNU Tar Manual available in texinfo format. If the info
reader and the tar documentation are properly installed on your
system, the command
info tar
should give you access to the complete manual.
You can also view the manual using the info mode in emacs(1), or
find it in various formats online at
http://www.gnu.org/software/tar/manual
If any discrepancies occur between this manpage and the GNU Tar
Manual, the later shall be considered the authoritative source.
DESCRIPTION
GNU tar is an archiving program designed to store multiple files
in a single file (an archive), and to manipulate such archives.
The archive can be either a regular file or a device (e.g. a tape
drive, hence the name of the program, which stands for tape
archiver), which can be located either on the local or on a
remote machine.
Option styles
Options to GNU tar can be given in three different styles. In
traditional style, the first argument is a cluster of option
letters and all subsequent arguments supply arguments to those
options that require them. The arguments are read in the same
order as the option letters. Any command line words that remain
after all options has been processed are treated as non-optional
arguments: file or archive member names.
For example, the c option requires creating the archive, the v
option requests the verbose operation, and the f option takes an
argument that sets the name of the archive to operate upon. The
following command, written in the traditional style, instructs
tar to store all files from the directory /etc into the archive
file etc.tar verbosely listing the files being archived:
tar cfv etc.tar /etc
In UNIX or short-option style, each option letter is prefixed
with a single dash, as in other command line utilities. If an
option takes argument, the argument follows it, either as a
separate command line word, or immediately following the option.
However, if the option takes an optional argument, the argument
must follow the option letter without any intervening whitespace,
as in -g/tmp/snar.db.
Any number of options not taking arguments can be clustered
together after a single dash, e.g. -vkp. Options that take
arguments (whether mandatory or optional), can appear at the end
of such a cluster, e.g. -vkpf a.tar.
The example command above written in the short-option style could
look like:
tar -cvf etc.tar /etc
or
tar -c -v -f etc.tar /etc
In GNU or long-option style, each option begins with two dashes
and has a meaningful name, consisting of lower-case letters and
dashes. When used, the long option can be abbreviated to its
initial letters, provided that this does not create ambiguity.
Arguments to long options are supplied either as a separate
command line word, immediately following the option, or separated
from the option by an equals sign with no intervening whitespace.
Optional arguments must always use the latter method.
Here are several ways of writing the example command in this
style:
tar --create --file etc.tar --verbose /etc
or (abbreviating some options):
tar --cre --file=etc.tar --verb /etc
The options in all three styles can be intermixed, although doing
so with old options is not encouraged.
Operation mode
The options listed in the table below tell GNU tar what operation
it is to perform. Exactly one of them must be given. Meaning of
non-optional arguments depends on the operation mode requested.
-A, --catenate, --concatenate
Append archive to the end of another archive. The
arguments are treated as the names of archives to append.
All archives must be of the same format as the archive
they are appended to, otherwise the resulting archive
might be unusable with non-GNU implementations of tar.
Notice also that when more than one archive is given, the
members from archives other than the first one will be
accessible in the resulting archive only if using the -i
(--ignore-zeros) option.
Compressed archives cannot be concatenated.
-c, --create
Create a new archive. Arguments supply the names of the
files to be archived. Directories are archived
recursively, unless the --no-recursion option is given.
-d, --diff, --compare
Find differences between archive and file system. The
arguments are optional and specify archive members to
compare. If not given, the current working directory is
assumed.
--delete
Delete from the archive. The arguments supply names of
the archive members to be removed. At least one argument
must be given.
This option does not operate on compressed archives.
There is no short option equivalent.
-r, --append
Append files to the end of an archive. Arguments have the
same meaning as for -c (--create).
-t, --list
List the contents of an archive. Arguments are optional.
When given, they specify the names of the members to list.
--test-label
Test the archive volume label and exit. When used without
arguments, it prints the volume label (if any) and exits
with status 0. When one or more command line arguments
are given. tar compares the volume label with each
argument. It exits with code 0 if a match is found, and
with code 1 otherwise. No output is displayed, unless
used together with the -v (--verbose) option.
There is no short option equivalent for this option.
-u, --update
Append files which are newer than the corresponding copy
in the archive. Arguments have the same meaning as with
-c and -r options. Notice, that newer files don't replace
their old archive copies, but instead are appended to the
end of archive. The resulting archive can thus contain
several members of the same name, corresponding to various
versions of the same file.
-x, --extract, --get
Extract files from an archive. Arguments are optional.
When given, they specify names of the archive members to
be extracted.
--show-defaults
Show built-in defaults for various tar options and exit.
No arguments are allowed.
-?, --help
Display a short option summary and exit. No arguments
allowed.
--usage
Display a list of available options and exit. No
arguments allowed.
--version
Print program version and copyright information and exit.
OPTIONS
Operation modifiers
--check-device
Check device numbers when creating incremental archives
(default).
-g, --listed-incremental=FILE
Handle new GNU-format incremental backups. FILE is the
name of a snapshot file, where tar stores additional
information which is used to decide which files changed
since the previous incremental dump and, consequently,
must be dumped again. If FILE does not exist when
creating an archive, it will be created and all files will
be added to the resulting archive (the level 0 dump). To
create incremental archives of non-zero level N, create a
copy of the snapshot file created during the level N-1,
and use it as FILE.
When listing or extracting, the actual contents of FILE is
not inspected, it is needed only due to syntactical
requirements. It is therefore common practice to use
/dev/null in its place.
--hole-detection=METHOD
Use METHOD to detect holes in sparse files. This option
implies --sparse. Valid values for METHOD are seek and
raw. Default is seek with fallback to raw when not
applicable.
-G, --incremental
Handle old GNU-format incremental backups.
--ignore-failed-read
Do not exit with nonzero on unreadable files.
--level=NUMBER
Set dump level for created listed-incremental archive.
Currently only --level=0 is meaningful: it instructs tar
to truncate the snapshot file before dumping, thereby
forcing a level 0 dump.
-n, --seek
Assume the archive is seekable. Normally tar determines
automatically whether the archive can be seeked or not.
This option is intended for use in cases when such
recognition fails. It takes effect only if the archive is
open for reading (e.g. with --list or --extract options).
--no-check-device
Do not check device numbers when creating incremental
archives.
--no-seek
Assume the archive is not seekable.
--occurrence[=N]
Process only the Nth occurrence of each file in the
archive. This option is valid only when used with one of
the following subcommands: --delete, --diff, --extract or
--list and when a list of files is given either on the
command line or via the -T option. The default N is 1.
--restrict
Disable the use of some potentially harmful options.
--sparse-version=MAJOR[.MINOR]
Set version of the sparse format to use (implies
--sparse). This option implies --sparse. Valid argument
values are 0.0, 0.1, and 1.0. For a detailed discussion
of sparse formats, refer to the GNU Tar Manual, appendix
D, "Sparse Formats". Using info reader, it can be
accessed running the following command: info tar 'Sparse
Formats'.
-S, --sparse
Handle sparse files efficiently. Some files in the file
system may have segments which were actually never written
(quite often these are database files created by such
systems as DBM). When given this option, tar attempts to
determine if the file is sparse prior to archiving it, and
if so, to reduce the resulting archive size by not dumping
empty parts of the file.
Overwrite control
These options control tar actions when extracting a file over an
existing copy on disk.
-k, --keep-old-files
Don't replace existing files when extracting.
--keep-newer-files
Don't replace existing files that are newer than their
archive copies.
--keep-directory-symlink
Don't replace existing symlinks to directories when
extracting.
--no-overwrite-dir
Preserve metadata of existing directories.
--one-top-level[=DIR]
Extract all files into DIR, or, if used without argument,
into a subdirectory named by the base name of the archive
(minus standard compression suffixes recognizable by
--auto-compress).
--overwrite
Overwrite existing files when extracting.
--overwrite-dir
Overwrite metadata of existing directories when extracting
(default).
--recursive-unlink
Recursively remove all files in the directory prior to
extracting it.
--remove-files
Remove files from disk after adding them to the archive.
--skip-old-files
Don't replace existing files when extracting, silently
skip over them.
-U, --unlink-first
Remove each file prior to extracting over it.
-W, --verify
Verify the archive after writing it.
Output stream selection
--ignore-command-error
Ignore subprocess exit codes.
--no-ignore-command-error
Treat non-zero exit codes of children as error (default).
-O, --to-stdout
Extract files to standard output.
--to-command=COMMAND
Pipe extracted files to COMMAND. The argument is the
pathname of an external program, optionally with command
line arguments. The program will be invoked and the
contents of the file being extracted supplied to it on its
standard input. Additional data will be supplied via the
following environment variables:
TAR_FILETYPE
Type of the file. It is a single letter with the
following meaning:
f Regular file
d Directory
l Symbolic link
h Hard link
b Block device
c Character device
Currently only regular files are supported.
TAR_MODE
File mode, an octal number.
TAR_FILENAME
The name of the file.
TAR_REALNAME
Name of the file as stored in the archive.
TAR_UNAME
Name of the file owner.
TAR_GNAME
Name of the file owner group.
TAR_ATIME
Time of last access. It is a decimal number,
representing seconds since the Epoch. If the
archive provides times with nanosecond precision,
the nanoseconds are appended to the timestamp after
a decimal point.
TAR_MTIME
Time of last modification.
TAR_CTIME
Time of last status change.
TAR_SIZE
Size of the file.
TAR_UID
UID of the file owner.
TAR_GID
GID of the file owner.
Additionally, the following variables contain information
about tar operation mode and the archive being processed:
TAR_VERSION
GNU tar version number.
TAR_ARCHIVE
The name of the archive tar is processing.
TAR_BLOCKING_FACTOR
Current blocking factor, i.e. number of 512-byte
blocks in a record.
TAR_VOLUME
Ordinal number of the volume tar is processing (set
if reading a multi-volume archive).
TAR_FORMAT
Format of the archive being processed. One of:
gnu, oldgnu, posix, ustar, v7.
TAR_SUBCOMMAND
A short option (with a leading dash) describing the
operation tar is executing.
Handling of file attributes
--atime-preserve[=METHOD]
Preserve access times on dumped files, either by restoring
the times after reading (METHOD=replace, this is the
default) or by not setting the times in the first place
(METHOD=system)
--delay-directory-restore
Delay setting modification times and permissions of
extracted directories until the end of extraction. Use
this option when extracting from an archive which has
unusual member ordering.
--group=NAME[:GID]
Force NAME as group for added files. If GID is not
supplied, NAME can be either a user name or numeric GID.
In this case the missing part (GID or name) will be
inferred from the current host's group database.
When used with --group-map=FILE, affects only those files
whose owner group is not listed in FILE.
--group-map=FILE
Read group translation map from FILE. Empty lines are
ignored. Comments are introduced with # sign and extend
to the end of line. Each non-empty line in FILE defines
translation for a single group. It must consist of two
fields, delimited by any amount of whitespace:
OLDGRP NEWGRP[:NEWGID]
OLDGRP is either a valid group name or a GID prefixed with
+. Unless NEWGID is supplied, NEWGRP must also be either
a valid group name or a +GID. Otherwise, both NEWGRP and
NEWGID need not be listed in the system group database.
As a result, each input file with owner group OLDGRP will
be stored in archive with owner group NEWGRP and GID
NEWGID.
--mode=CHANGES
Force symbolic mode CHANGES for added files.
--mtime=DATE-OR-FILE
Set mtime for added files. DATE-OR-FILE is either a
date/time in almost arbitrary format, or the name of an
existing file. In the latter case the mtime of that file
will be used.
-m, --touch
Don't extract file modified time.
--no-delay-directory-restore
Cancel the effect of the prior --delay-directory-restore
option.
--no-same-owner
Extract files as yourself (default for ordinary users).
--no-same-permissions
Apply the user's umask when extracting permissions from
the archive (default for ordinary users).
--numeric-owner
Always use numbers for user/group names.
--owner=NAME[:UID]
Force NAME as owner for added files. If UID is not
supplied, NAME can be either a user name or numeric UID.
In this case the missing part (UID or name) will be
inferred from the current host's user database.
When used with --owner-map=FILE, affects only those files
whose owner is not listed in FILE.
--owner-map=FILE
Read owner translation map from FILE. Empty lines are
ignored. Comments are introduced with # sign and extend
to the end of line. Each non-empty line in FILE defines
translation for a single UID. It must consist of two
fields, delimited by any amount of whitespace:
OLDUSR NEWUSR[:NEWUID]
OLDUSR is either a valid user name or a UID prefixed with
+. Unless NEWUID is supplied, NEWUSR must also be either
a valid user name or a +UID. Otherwise, both NEWUSR and
NEWUID need not be listed in the system user database.
As a result, each input file owned by OLDUSR will be
stored in archive with owner name NEWUSR and UID NEWUID.
-p, --preserve-permissions, --same-permissions
extract information about file permissions (default for
superuser)
--same-owner
Try extracting files with the same ownership as exists in
the archive (default for superuser).
-s, --preserve-order, --same-order
Sort names to extract to match archive
--sort=ORDER
When creating an archive, sort directory entries according
to ORDER, which is one of none, name, or inode.
The default is --sort=none, which stores archive members
in the same order as returned by the operating system.
Using --sort=name ensures the member ordering in the
created archive is uniform and reproducible.
Using --sort=inode reduces the number of disk seeks made
when creating the archive and thus can considerably speed
up archivation. This sorting order is supported only if
the underlying system provides the necessary information.
Extended file attributes
--acls Enable POSIX ACLs support.
--no-acls
Disable POSIX ACLs support.
--selinux
Enable SELinux context support.
--no-selinux
Disable SELinux context support.
--xattrs
Enable extended attributes support.
--no-xattrs
Disable extended attributes support.
--xattrs-exclude=PATTERN
Specify the exclude pattern for xattr keys. PATTERN is a
globbing pattern, e.g. --xattrs-exclude='user.*' to
include only attributes from the user namespace.
--xattrs-include=PATTERN
Specify the include pattern for xattr keys. PATTERN is a
globbing pattern.
Device selection and switching
-f, --file=ARCHIVE
Use archive file or device ARCHIVE. If this option is not
given, tar will first examine the environment variable
`TAPE'. If it is set, its value will be used as the
archive name. Otherwise, tar will assume the compiled-in
default. The default value can be inspected either using
the --show-defaults option, or at the end of the tar
--help output.
An archive name that has a colon in it specifies a file or
device on a remote machine. The part before the colon is
taken as the machine name or IP address, and the part
after it as the file or device pathname, e.g.:
--file=remotehost:/dev/sr0
An optional username can be prefixed to the hostname,
placing a @ sign between them.
By default, the remote host is accessed via the rsh(1)
command. Nowadays it is common to use ssh(1) instead.
You can do so by giving the following command line option:
--rsh-command=/usr/bin/ssh
The remote machine should have the rmt(8) command
installed. If its pathname does not match tar's default,
you can inform tar about the correct pathname using the
--rmt-command option.
--force-local
Archive file is local even if it has a colon.
-F, --info-script=COMMAND, --new-volume-script=COMMAND
Run COMMAND at the end of each tape (implies -M). The
command can include arguments. When started, it will
inherit tar's environment plus the following variables:
TAR_VERSION
GNU tar version number.
TAR_ARCHIVE
The name of the archive tar is processing.
TAR_BLOCKING_FACTOR
Current blocking factor, i.e. number of 512-byte
blocks in a record.
TAR_VOLUME
Ordinal number of the volume tar is processing (set
if reading a multi-volume archive).
TAR_FORMAT
Format of the archive being processed. One of:
gnu, oldgnu, posix, ustar, v7.
TAR_SUBCOMMAND
A short option (with a leading dash) describing the
operation tar is executing.
TAR_FD File descriptor which can be used to communicate
the new volume name to tar.
If the info script fails, tar exits; otherwise, it begins
writing the next volume.
-L, --tape-length=N
Change tape after writing Nx1024 bytes. If N is followed
by a size suffix (see the subsection Size suffixes below),
the suffix specifies the multiplicative factor to be used
instead of 1024.
This option implies -M.
-M, --multi-volume
Create/list/extract multi-volume archive.
--rmt-command=COMMAND
Use COMMAND instead of rmt when accessing remote archives.
See the description of the -f option, above.
--rsh-command=COMMAND
Use COMMAND instead of rsh when accessing remote archives.
See the description of the -f option, above.
--volno-file=FILE
When this option is used in conjunction with
--multi-volume, tar will keep track of which volume of a
multi-volume archive it is working in FILE.
Device blocking
-b, --blocking-factor=BLOCKS
Set record size to BLOCKSx512 bytes.
-B, --read-full-records
When listing or extracting, accept incomplete input
records after end-of-file marker.
-i, --ignore-zeros
Ignore zeroed blocks in archive. Normally two consecutive
512-blocks filled with zeroes mean EOF and tar stops
reading after encountering them. This option instructs it
to read further and is useful when reading archives
created with the -A option.
--record-size=NUMBER
Set record size. NUMBER is the number of bytes per
record. It must be multiple of 512. It can can be
suffixed with a size suffix, e.g. --record-size=10K, for
10 Kilobytes. See the subsection Size suffixes, for a
list of valid suffixes.
Archive format selection
-H, --format=FORMAT
Create archive of the given format. Valid formats are:
gnu GNU tar 1.13.x format
oldgnu GNU format as per tar <= 1.12.
pax, posix
POSIX 1003.1-2001 (pax) format.
ustar POSIX 1003.1-1988 (ustar) format.
v7 Old V7 tar format.
--old-archive, --portability
Same as --format=v7.
--pax-option=keyword[[:]=value][,keyword[[:]=value]]...
Control pax keywords when creating PAX archives (-H pax).
This option is equivalent to the -o option of the pax(1)
utility.
--posix
Same as --format=posix.
-V, --label=TEXT
Create archive with volume name TEXT. If listing or
extracting, use TEXT as a globbing pattern for volume
name.
Compression options
-a, --auto-compress
Use archive suffix to determine the compression program.
-I, --use-compress-program=COMMAND
Filter data through COMMAND. It must accept the -d
option, for decompression. The argument can contain
command line options.
-j, --bzip2
Filter the archive through bzip2(1).
-J, --xz
Filter the archive through xz(1).
--lzip Filter the archive through lzip(1).
--lzma Filter the archive through lzma(1).
--lzop Filter the archive through lzop(1).
--no-auto-compress
Do not use archive suffix to determine the compression
program.
-z, --gzip, --gunzip, --ungzip
Filter the archive through gzip(1).
-Z, --compress, --uncompress
Filter the archive through compress(1).
--zstd Filter the archive through zstd(1).
Local file selection
--add-file=FILE
Add FILE to the archive (useful if its name starts with a
dash).
--backup[=CONTROL]
Backup before removal. The CONTROL argument, if supplied,
controls the backup policy. Its valid values are:
none, off
Never make backups.
t, numbered
Make numbered backups.
nil, existing
Make numbered backups if numbered backups exist,
simple backups otherwise.
never, simple
Always make simple backups
If CONTROL is not given, the value is taken from the
VERSION_CONTROL environment variable. If it is not set,
existing is assumed.
-C, --directory=DIR
Change to DIR before performing any operations. This
option is order-sensitive, i.e. it affects all options
that follow.
--exclude=PATTERN
Exclude files matching PATTERN, a glob(3)-style wildcard
pattern.
--exclude-backups
Exclude backup and lock files.
--exclude-caches
Exclude contents of directories containing file
CACHEDIR.TAG, except for the tag file itself.
--exclude-caches-all
Exclude directories containing file CACHEDIR.TAG and the
file itself.
--exclude-caches-under
Exclude everything under directories containing
CACHEDIR.TAG
--exclude-ignore=FILE
Before dumping a directory, see if it contains FILE. If
so, read exclusion patterns from this file. The patterns
affect only the directory itself.
--exclude-ignore-recursive=FILE
Same as --exclude-ignore, except that patterns from FILE
affect both the directory and all its subdirectories.
--exclude-tag=FILE
Exclude contents of directories containing FILE, except
for FILE itself.
--exclude-tag-all=FILE
Exclude directories containing FILE.
--exclude-tag-under=FILE
Exclude everything under directories containing FILE.
--exclude-vcs
Exclude version control system directories.
--exclude-vcs-ignores
Exclude files that match patterns read from VCS-specific
ignore files. Supported files are: .cvsignore,
.gitignore, .bzrignore, and .hgignore.
-h, --dereference
Follow symlinks; archive and dump the files they point to.
--hard-dereference
Follow hard links; archive and dump the files they refer
to.
-K, --starting-file=MEMBER
Begin at the given member in the archive.
--newer-mtime=DATE
Work on files whose data changed after the DATE. If DATE
starts with / or . it is taken to be a file name; the
mtime of that file is used as the date.
--no-null
Disable the effect of the previous --null option.
--no-recursion
Avoid descending automatically in directories.
--no-unquote
Do not unquote input file or member names.
--no-verbatim-files-from
Treat each line read from a file list as if it were
supplied in the command line. I.e., leading and trailing
whitespace is removed and, if the resulting string begins
with a dash, it is treated as tar command line option.
This is the default behavior. The
--no-verbatim-files-from option is provided as a way to
restore it after --verbatim-files-from option.
This option is positional: it affects all --files-from
options that occur after it in, until
--verbatim-files-from option or end of line, whichever
occurs first.
It is implied by the --no-null option.
--null Instruct subsequent -T options to read null-terminated
names verbatim (disables special handling of names that
start with a dash).
See also --verbatim-files-from.
-N, --newer=DATE, --after-date=DATE
Only store files newer than DATE. If DATE starts with /
or . it is taken to be a file name; the mtime of that file
is used as the date.
--one-file-system
Stay in local file system when creating archive.
-P, --absolute-names
Don't strip leading slashes from file names when creating
archives.
--recursion
Recurse into directories (default).
--suffix=STRING
Backup before removal, override usual suffix. Default
suffix is ~, unless overridden by environment variable
SIMPLE_BACKUP_SUFFIX.
-T, --files-from=FILE
Get names to extract or create from FILE.
Unless specified otherwise, the FILE must contain a list
of names separated by ASCII LF (i.e. one name per line).
The names read are handled the same way as command line
arguments. They undergo quote removal and word splitting,
and any string that starts with a - is handled as tar
command line option.
If this behavior is undesirable, it can be turned off
using the --verbatim-files-from option.
The --null option instructs tar that the names in FILE are
separated by ASCII NUL character, instead of LF. It is
useful if the list is generated by find(1) -print0
predicate.
--unquote
Unquote file or member names (default).
--verbatim-files-from
Treat each line obtained from a file list as a file name,
even if it starts with a dash. File lists are supplied
with the --files-from (-T) option. The default behavior
is to handle names supplied in file lists as if they were
typed in the command line, i.e. any names starting with a
dash are treated as tar options. The
--verbatim-files-from option disables this behavior.
This option affects all --files-from options that occur
after it in the command line. Its effect is reverted by
the --no-verbatim-files-from} option.
This option is implied by the --null option.
See also --add-file.
-X, --exclude-from=FILE
Exclude files matching patterns listed in FILE.
File name transformations
--strip-components=NUMBER
Strip NUMBER leading components from file names on
extraction.
--transform=EXPRESSION, --xform=EXPRESSION
Use sed replace EXPRESSION to transform file names.
File name matching options
These options affect both exclude and include patterns.
--anchored
Patterns match file name start.
--ignore-case
Ignore case.
--no-anchored
Patterns match after any / (default for exclusion).
--no-ignore-case
Case sensitive matching (default).
--no-wildcards
Verbatim string matching.
--no-wildcards-match-slash
Wildcards do not match /.
--wildcards
Use wildcards (default for exclusion).
--wildcards-match-slash
Wildcards match / (default for exclusion).
Informative output
--checkpoint[=N]
Display progress messages every Nth record (default 10).
--checkpoint-action=ACTION
Run ACTION on each checkpoint.
--clamp-mtime
Only set time when the file is more recent than what was
given with --mtime.
--full-time
Print file time to its full resolution.
--index-file=FILE
Send verbose output to FILE.
-l, --check-links
Print a message if not all links are dumped.
--no-quote-chars=STRING
Disable quoting for characters from STRING.
--quote-chars=STRING
Additionally quote characters from STRING.
--quoting-style=STYLE
Set quoting style for file and member names. Valid values
for STYLE are literal, shell, shell-always, c, c-maybe,
escape, locale, clocale.
-R, --block-number
Show block number within archive with each message.
--show-omitted-dirs
When listing or extracting, list each directory that does
not match search criteria.
--show-transformed-names, --show-stored-names
Show file or archive names after transformation by --strip
and --transform options.
--totals[=SIGNAL]
Print total bytes after processing the archive. If SIGNAL
is given, print total bytes when this signal is delivered.
Allowed signals are: SIGHUP, SIGQUIT, SIGINT, SIGUSR1, and
SIGUSR2. The SIG prefix can be omitted.
--utc Print file modification times in UTC.
-v, --verbose
Verbosely list files processed. Each instance of this
option on the command line increases the verbosity level
by one. The maximum verbosity level is 3. For a detailed
discussion of how various verbosity levels affect tar's
output, please refer to GNU Tar Manual, subsection 2.5.1
"The --verbose Option".
--warning=KEYWORD
Enable or disable warning messages identified by KEYWORD.
The messages are suppressed if KEYWORD is prefixed with
no- and enabled otherwise.
Multiple --warning messages accumulate.
Keywords controlling general tar operation:
all Enable all warning messages. This is the default.
none Disable all warning messages.
filename-with-nuls
"%s: file name read contains nul character"
alone-zero-block
"A lone zero block at %s"
Keywords applicable for tar --create:
cachedir
"%s: contains a cache directory tag %s; %s"
file-shrank
"%s: File shrank by %s bytes; padding with zeros"
xdev "%s: file is on a different filesystem; not dumped"
file-ignored
"%s: Unknown file type; file ignored"
"%s: socket ignored"
"%s: door ignored"
file-unchanged
"%s: file is unchanged; not dumped"
ignore-archive
"%s: archive cannot contain itself; not dumped"
file-removed
"%s: File removed before we read it"
file-changed
"%s: file changed as we read it"
failed-read
Suppresses warnings about unreadable files or
directories. This keyword applies only if used
together with the --ignore-failed-read option.
Keywords applicable for tar --extract:
existing-file
"%s: skipping existing file"
timestamp
"%s: implausibly old time stamp %s"
"%s: time stamp %s is %s s in the future"
contiguous-cast
"Extracting contiguous files as regular files"
symlink-cast
"Attempting extraction of symbolic links as hard
links"
unknown-cast
"%s: Unknown file type '%c', extracted as normal
file"
ignore-newer
"Current %s is newer or same age"
unknown-keyword
"Ignoring unknown extended header keyword '%s'"
decompress-program
Controls verbose description of failures occurring
when trying to run alternative decompressor
programs. This warning is disabled by default
(unless --verbose is used). A common example of
what you can get when using this warning is:
$ tar --warning=decompress-program -x -f archive.Z
tar (child): cannot run compress: No such file or directory
tar (child): trying gzip
This means that tar first tried to decompress
archive.Z using compress, and, when that failed,
switched to gzip.
record-size
"Record size = %lu blocks"
Keywords controlling incremental extraction:
rename-directory
"%s: Directory has been renamed from %s"
"%s: Directory has been renamed"
new-directory
"%s: Directory is new"
xdev "%s: directory is on a different device: not
purging"
bad-dumpdir
"Malformed dumpdir: 'X' never used"
-w, --interactive, --confirmation
Ask for confirmation for every action.
Compatibility options
-o When creating, same as --old-archive. When extracting,
same as --no-same-owner.
Size suffixes
Suffix Units Byte Equivalent
b Blocks SIZE x 512
B Kilobytes SIZE x 1024
c Bytes SIZE
G Gigabytes SIZE x 1024^3
K Kilobytes SIZE x 1024
k Kilobytes SIZE x 1024
M Megabytes SIZE x 1024^2
P Petabytes SIZE x 1024^5
T Terabytes SIZE x 1024^4
w Words SIZE x 2
RETURN VALUE
Tar exit code indicates whether it was able to successfully
perform the requested operation, and if not, what kind of error
occurred.
0 Successful termination.
1 Some files differ. If tar was invoked with the --compare
(--diff, -d) command line option, this means that some
files in the archive differ from their disk counterparts.
If tar was given one of the --create, --append or --update
options, this exit code means that some files were changed
while being archived and so the resulting archive does not
contain the exact copy of the file set.
2 Fatal error. This means that some fatal, unrecoverable
error occurred.
If a subprocess that had been invoked by tar exited with a
nonzero exit code, tar itself exits with that code as well. This
can happen, for example, if a compression option (e.g. -z) was
used and the external compressor program failed. Another example
is rmt failure during backup to a remote device.
SEE ALSO
bzip2(1), compress(1), gzip(1), lzma(1), lzop(1), rmt(8),
symlink(7), xz(1), zstd(1).
Complete tar manual: run info tar or use emacs(1) info mode to
read it.
Online copies of GNU tar documentation in various formats can be
found at:
http://www.gnu.org/software/tar/manual
BUG REPORTS
Report bugs to <bug-tar@gnu.org>.
COPYRIGHT
Copyright © 2013-2019 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute
it. There is NO WARRANTY, to the extent permitted by law.
COLOPHON
This page is part of the tar (an archiver program) project.
Information about the project can be found at
⟨http://savannah.gnu.org/projects/tar/⟩. If you have a bug report
for this manual page, see
⟨http://savannah.gnu.org/bugs/?group=tar⟩. This page was
obtained from the project's upstream Git repository
⟨git://git.savannah.gnu.org/tar.git⟩ on 2023-06-23. (At that
time, the date of the most recent commit that was found in the
repository was 2023-06-18.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.orgtldr-pages
> tldr tar
tldr-pages
tldr-pages
Crowd sourced documentation files:
Guidelines for contributing and translating documentation, including instructions for authoring markdown
- Similar to best practices found in literature
The {tldr} R package
The {tldr} R package
The {tldr} R package
The {tldr} R package
Writing {tldr} Documentation
Writing {tldr} Documentation
#' Safe multiplication of numeric vectors
#'
#' Multiplies vectors `a` and `b`, component-wise.
#' Does not recycle arguments, errors informatively if `length(a) != length(b)`.
#' Also ensures both `a` and `b` are both `numeric`.
#'
#' @param a Multiplier, numeric vector
#' @param b Multiplicand, numeric vector with same length as `a`
#' @paramtldr a Multiplier
#' @paramtldr b Multiplicand
#'
#' @exampletldr Multiply scalars:
#' \code{multiply(1, 2)}
#'
#' @exampletldr Multiply vectors, component-wise:
#' \code{multiply(1:10, rep(2, 10))}
#'
#' @exampletldr Values are not recycled:
#' \code{multiply(1:10, 1) # errors}
#'
#' @examples
#' # Behavior is the same as infix `%*%` when arguments are scalars:
#' (res_1 <- multiply(1, 2))
#' (res_2 <- 1 * 2)
#' identical(res_1, res_2)
#'
#' # also when arguments are vectors of same length:
#' (res_1_vec <- multiply(1:10, 11:20))
#' (res_2_vec <- 1:10 * 11:20)
#' identical(res_1_vec, res_2_vec)
#'
#' \dontrun{
#'
#' # However, `multiply()` does not recycle vectors:
#' 1:10 * 1
#' multiply(1:10, 1)
#'
#' 1:10 * 0:1
#' multiply(1:10, 0:1)
#'}
#'
#' @return A numeric vector with length equal to both `length(a)` and `length(b)`
#' @export
multiply <- function(a, b) {
if (!is.numeric(a)) stop("a must be numeric")
if (!is.numeric(b)) stop("b must be numeric")
if (length(a) != length(b)) stop("a and b must be vectors of the same length")
a * b
}tldrExample/R/multiply.R
Writing {tldr} Documentation
% Generated by roxygen2: do not edit by hand
\name{multiply}
\alias{multiply}
\title{Safe multiplication of numeric vectors}
\arguments{
\item{a}{Multiplier}
\item{b}{Multiplicand
}
}
\details{
Multiply scalars:
\code{multiply(1, 2)}
Multiply vectors, component-wise:
\code{multiply(1:10, rep(2, 10))}
Values are not recycled:
\code{multiply(1:10, 1) # errors}
}
\value{
A numeric vector with length equal to both \code{length(a)} and \code{length(b)}
}/inst/tldr/multiply.Rd
Writing {tldr} Documentation
% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/multiply.R
\name{multiply}
\alias{multiply}
\title{Safe multiplication of numeric vectors}
\usage{
multiply(a, b)
}
\arguments{
\item{a}{Multiplier, numeric vector}
\item{b}{Multiplicand, numeric vector with same length as \code{a}}
}
\value{
A numeric vector with length equal to both \code{length(a)} and \code{length(b)}
}
\description{
Multiplies vectors \code{a} and \code{b}, component-wise.
Does not recycle arguments, errors informatively if \code{length(a) != length(b)}.
Also ensures both \code{a} and \code{b} are both \code{numeric}.
}
\examples{
# Behavior is the same as infix `\%*\%` when arguments are scalars:
(res_1 <- multiply(1, 2))
(res_2 <- 1 * 2)
identical(res_1, res_2)
# also when arguments are vectors of same length:
(res_1_vec <- multiply(1:10, 11:20))
(res_2_vec <- 1:10 * 11:20)
identical(res_1_vec, res_2_vec)
\dontrun{
# However, `multiply()` does not recycle vectors:
1:10 * 1
multiply(1:10, 1)
1:10 * 0:1
multiply(1:10, 0:1)
}
}tldrExample/man/multiply.Rd
{tldrDocs}
{tldrDocs}
{tldrDocs}
{tldrDocs}
Intended to be crowd-sourced, similar to tldr-pages.
- Collaboration facilitated by GitHub version control tools
We are currently developing guidelines and more robust documentation for authoring {tldr} documentation for base functions.
References
Bhatti J, Corleissen ZS, Lambourne J, Nunez D, Waterhouse H. 2021. Docs for Developers: An Engineer’s Field Guide to Technical Writing. Berkeley, CA: Apress.
Burow R, Weber G. 1996. Example explanation in learning environments In: Goos G, Hartmanis J, Leeuwen J, Frasson C, Gauthier G, Lesgold A, eds. Intelligent Tutoring Systems. Berlin, Heidelberg: Springer Berlin Heidelberg, 457–465.
Ko AJ, Myers BA, Aung HH. 2004. Six Learning Barriers in End-User Programming Systems In: 2004 IEEE Symposium on Visual Languages - Human Centric Computing. Rome, Italy: IEEE, 199–206.
McLellan SG, Roesler AW, Tempest JT, Spinuzzi CI. 1998. Building more usable APIs. IEEE Software 15: 78–86.
Nasehi SM, Sillito J, Maurer F, Burns C. 2012. What makes a good code example?: A study of programming Q&A in StackOverflow In: 2012 28th IEEE International Conference on Software Maintenance (ICSM).25–34.
Neal LR. 1989. A system for example-based programming. ACM SIGCHI Bulletin 20: 63–68.
Plass JL, Moreno R, Brünken R (Eds.). 2010. Cognitive Load Theory. Cambridge University Press.
Redmiles DF. 1993. Reducing the variability of programmers’ performance through explained examples In: Proceedings of the SIGCHI conference on Human factors in computing systems - CHI ’93. Amsterdam, The Netherlands: ACM Press, 67–73.
Robillard MP. 2009. What Makes APIs Hard to Learn? Answers from Developers. IEEE Software 26: 27–34.
Rosson MB, Carroll JM. 1996. The reuse of uses in Smalltalk programming. ACM Transactions on Computer-Human Interaction 3: 219–253.
Schank PK, Linn MC, Clancy MJ. 1993. Supporting Pascal programming with an on-line template library and case studies. International Journal of Man-Machine Studies 38: 1031–1048.
Wiedenbeck S. 2005. Facilitators and Inhibitors of End-User Development by Teachers in a School Environment In: 2005 IEEE Symposium on Visual Languages and Human-Centric Computing (VL/HCC’05). Dallas, TX, USA: IEEE, 215–222.
Thank you!
Supplemental Materials
{roxygen2} extension details
`tldrExample/R/multiply.R` |>
tldr_roclet() |>
roclet_process.roclet_tldr() |>
block_to_rd_tldr() |>
roxy_tag_rd_tldr() |>
# methods: .roxy_tag_rd_exampletldr(), .roxy_tag_rd_paramtldr()
roxy_tag_parse() |>
# methods: .rd_section_exampletldr(), .rd_section_paramtldr()
format() |>
# methods: .rd_section_exampletldr(), .rd_section_paramtldr()
roclet_output.roclet_tldr() ->
`tldrExample/inst/tldr/multiply.Rd`
`tldrExample/inst/tldr/multiply.Rd` |>
install.packages() ->
`ubuntu/R/x86_64-pc-linux-gnu-library/4.3/tldrExample/tldr/multiply.Rd`tldr() implementation details
Same evaluation as `?`()
Documenting data
James Otto (Alcon Laboratories)