For example I use Raspbian Stretch Lite
Type '7' Contiguous file is formally marked as reserved in the POSIX standard, but was meant to indicate files which ought to be contiguously allocated on disk. Few operating systems support creating such files explicitly, and hence most TAR programs do not support them, and will treat type 7 files as if they were type 0 regular.
This format is known as extended tar-format or pax -format. The new tar format allows users to add any type of vendor-tagged vendor-specific enhancements.
InGNU tar supported the new format, though it does not write them as its default output from the tar program yet. The only exceptions are files that make use of extended features, such as longer file names. The additional information will be extracted as a plain text file along with the file it refers to.
This process copies an entire source directory tree including all special files, for example: Limitations[ edit ] The original tar format was created in the early days of UNIX, and despite current widespread use, many of its design features are considered dated.
InStar introduced support for ACLs and extended attributes, through its own extensions. Bsdtar uses the star extensions to support ACL's. Other formats have been created to address the shortcomings of tar. Operating system support[ edit ] Unix-like operating systems usually include tools to support tar files, as well as utilities commonly used to compress them, such as gzip and bzip2.
BSD-tar has been included in Microsoft Windows since Windows 10 April Update and there are otherwise multiple third party tools available to read and write these formats on Windows. Tarbomb[ edit ] "Tarbomb" redirects here.
It is not to be confused with zip bomb. A tarbomb, in hacker slangis a tar file that contains many files that extract into the working directory.
Such a tar file can create problems by overwriting files of the same name in the working directory, or mixing one project's files into another. It is at best an inconvenience to the user, who is obliged to identify and delete a number of files interspersed with the directory's other contents.
Such behavior is considered bad etiquette on the part of the archive's creator. A related problem is the use of absolute paths or parent directory references when creating tar files.
Files extracted from such archives will often be created in unusual locations outside the working directory and, like a tarbomb, have the potential to overwrite existing files. However, modern versions of FreeBSD and GNU tar do not create or extract absolute paths and parent-directory references by default, unless it is explicitly allowed with the flag -P or the option --absolute-names.
The bsdtar program, which is also available on many operating systems and is the default tar utility on Mac OS X v These commands do not extract any files, but display the names of all files in the archive.
If any are problematic, the user can create a new empty directory and extract the archive into it—or avoid the tar file entirely. Most graphical tools can display the contents of the archive before extracting them.
Vim can open tar archives and display their contents.
GNU Emacs is also able to open a tar archive and display its contents in a dired buffer. Random access[ edit ] Another weakness of the tar format compared to other archive formats like DAR or Zip is that there is no centralized location for the information about the contents of the file a "table of contents" of sortsso to list the names of the files that are in the archive, one must read through the entire archive and look for places where files start.
Also, to extract one small file from the archive, instead of being able to look up the offset in a table and go directly to that location, like other archive formats, with tar, one has to read through the entire archive, looking for the place where the desired file starts.
For large tar archives, this causes a big performance penalty, making tar archives unsuitable for situations that often require random access of individual files.
The possible reason for not using a centralized location of information is that tar was originally meant for tapes, which are bad at random access anyway: On the other hand, if the TOC were at the end-of-file as is the case with ZIP files, for examplereading the TOC would require that the tape be wound to the end, also taking up time and degrading the tape by excessive wear and tear.
Compression further complicates matters; as calculating compressed positions for a TOC at the start would need compression of everything before writing the TOC, a TOC with uncompressed positions is not really useful since one has to decompress everything anyway to get the right positions and decompressing a TOC at the end of the file might require decompressing the whole file anyway, too.
But today there are a number of add-on utilities which implement tar file indexing, thus enabling random access, both for raw tar files and for tar files compressed with gzip which is amenable to indexing. Such an index can be kept in a separate file, appended or prepended to the archive file.
When extracting such archive, usually the latter version of a file overwrites the former. This can create a non-explicit unobvious tarbomb, which technically does not contain files with absolute paths or referring parent directories, but still causes overwriting files outside current directory for example, archive may contain two files with the same path and filename, first of which is a symlink to some location outside current directory, and second of which is a regular file; then extracting such archive on some tar implementations may cause writing to the location pointed to by the symlink.
Key implementations[ edit ] Historically, many systems have implemented tar, and many general file archivers have at least partial support for tar often using one of the implementations below. The history of tar is a story of incompatibilities, known as the "tar wars".
Most tar implementations can also read and create cpio and pax the latter actually is a tar-format with POSIX extensions.
Key implementations in order of origin: GNU tar is the default on most Linux distributions.Dec 27, · This will overwrite all current contents, and it must be equal or greater size.
Use dd_rescue if you have it, dd conv=noerror,sync if you don't. If your drive has bad sectors, they'll stick out during this process, but that can't be helped.
(The origin of tar's record size appears to be the byte disk sectors used in the Version 7 Unix file system.) The final block of an archive is padded out to full length with zeros. Header [ edit ]. Unix & Linux Stack Exchange is a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems.
overwrite areas of the disk that are not currently occupied by files; No guarantees. An SSD can move sectors around if it needs to, some of the reserved space might be swapped with active space if the active. Console RAR manual. -o+ Overwrite all (default for updating archived files);-o- Skip existing files.-p[p] Encrypt files with the string as password while archiving.
Windows allows to set all three times, Unix – modification and last access, but not creation, DOS supports only the modification time. This guide shows practical examples for using the Linux unzip command, including listing the contents of a file and unzipping password-protected files However, you can use the -n switch if you want to not overwrite existing files.
Every file from the ZIP archive that has a name matching a file in the extracted folder will not overwrite. Pay attention, any mistake will overwrite your importand data. On destination all will be overwritten. If you try rescue data on damaged source disk, better use native sector size, usually this is bytes, and add option conv=notrunc.
otherwise holes in source dropped by bad sectors will be joined by sector shifting on destination.