tar - Tar file handling

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# tar(n) 0.13 tcllib "Tar file handling"

## Name

tar - Tar file creation, extraction & manipulation

## Synopsis

- package require Tcl 8.5 9
- package require tar ?0.13?

- ::tar::contents tarball ?-chan? ?-gzip?
- ::tar::stat tarball ?file? ?-chan? ?-gzip?
- ::tar::untar tarball args
- ::tar::get tarball fileName ?-chan? ?-gzip?
- ::tar::create tarball files args
- ::tar::add tarball files args
- ::tar::remove tarball files

## Description

Note: Starting with version 0.8 the tar reader commands (contents, stats, get, untar) support the GNU LongName extension (header type 'L') for large paths.

## BEWARE

For all commands, when using -chan ...

1. It is assumed that the channel was opened for reading, and configured for binary input.

2. It is assumed that the channel position is at the beginning of a legal tar file.

3. The commands will modify the channel position as they perform their task.

4. The commands will not close the channel.

5. In other words, the commands leave the channel in a state very likely unsuitable for use by further tar commands. Still doing so will very likely results in errors, bad data, etc. pp.

6. It is the responsibility of the user to seek the channel back to a suitable position.

7. When using a channel transformation which is not generally seekable, for example gunzip, then it is the responsibility of the user to (a) unstack the transformation before seeking the channel back to a suitable position, and (b) for restacking it after.

Regarding support for gzip compression:

1. Errors are thrown when attempting to read from compressed tar archives while compression support (i.e. ::zlib) is not available.

2. Errors are thrown when attempting to read an uncompressed tar archive when compression is requested by the user (-gzip).

   No errors are thrown when attempting to read a compressed tar archive when compression was not requested, and is supported. In that case the commands automatically activate the code handling the compression.

3. Errors are thrown when attempting to edit compressed tar archives. See the commands tar::add, and tar::remove. This is not supported.

4. Creation of compressed tar archives however is supported, as this sequentially writes the archive, allowing for streaming compression.

## COMMANDS

::tar::contents tarball ?-chan? ?-gzip?

  Returns a list of the files contained in tarball. The order is not sorted and depends on the order files were stored in the archive.

  If the option -chan is present tarball is interpreted as an open channel. It is assumed that the channel was opened for reading, and configured for binary input. The command will not close the channel.

::tar::stat tarball ?file? ?-chan? ?-gzip?

  Returns a nested dict containing information on the named ?file? in tarball, or all files if none is specified. The top level are pairs of filename and info. The info is a dict with the keys "mode uid gid size mtime type linkname uname gname devmajor devminor"

      % ::tar::stat tarball.tar
      foo.jpg {mode 0644 uid 1000 gid 0 size 7580 mtime 811903867 type file linkname {} uname user gname wheel devmajor 0 devminor 0}

  If the option -chan is present tarball is interpreted as an open channel. It is assumed that the channel was opened for reading, and configured for binary input. The command will not close the channel.

::tar::untar tarball args

  Extracts tarball. -file and -glob limit the extraction to files which exactly match or pattern match the given argument. No error is thrown if no files match. Returns a list of filenames extracted and the file size. The size will be null for non regular files. Leading path seperators are stripped so paths will always be relative.

  -dir dirName

    Directory to extract to. Uses pwd if none is specified

  -file fileName

    Only extract the file with this name. The name is matched against the complete path stored in the archive including directories.

  -glob pattern

    Only extract files patching this glob style pattern. The pattern is matched against the complete path stored in the archive.

  -nooverwrite

    Dont overwrite files that already exist

  -nomtime

    Leave the file modification time as the current time instead of setting it to the value in the archive.

  -noperms

    In Unix, leave the file permissions as the current umask instead of setting them to the values in the archive.

  -chan

    If this option is present tarball is interpreted as an open channel. It is assumed that the channel was opened for reading, and configured for binary input. The command will not close the channel.

      % foreach {file size} [::tar::untar tarball.tar -glob *.jpg] {
      puts "Extracted $file ($size bytes)"
      }

::tar::get tarball fileName ?-chan? ?-gzip?

  Returns the contents of fileName from the tarball.

      % set readme [::tar::get tarball.tar doc/README] {
      % puts $readme
      }

  If the option -chan is present tarball is interpreted as an open channel. It is assumed that the channel was opened for reading, and configured for binary input. The command will not close the channel.

  An error is thrown when fileName is not found in the tar archive.

::tar::create tarball files args

  Creates a new tar file containing the files. files must be specified as a single argument which is a proper list of filenames.

  -dereference

    Normally create will store links as an actual link pointing at a file that may or may not exist in the archive. Specifying this option will cause the actual file point to by the link to be stored instead.

  -chan

    If this option is present tarball is interpreted as an open channel. It is assumed that the channel was opened for writing, and configured for binary output. The command will not close the channel.

      % ::tar::create new.tar [glob -nocomplain file*]
      % ::tar::contents new.tar
      file1 file2 file3

::tar::add tarball files args

  Appends files to the end of the existing tarball. files must be specified as a single argument which is a proper list of filenames.

  -dereference

    Normally add will store links as an actual link pointing at a file that may or may not exist in the archive. Specifying this option will cause the actual file point to by the link to be stored instead.

  -prefix string

    Normally add will store files under exactly the name specified as argument. Specifying a ?-prefix? causes the string to be prepended to every name.

  -quick

    The only sure way to find the position in the tarball where new files can be added is to read it from start, but if tarball was written with a "blocksize" of 1 (as this package does) then one can alternatively find this position by seeking from the end. The ?-quick? option tells add to do the latter.

::tar::remove tarball files

  Removes files from the tarball. No error will result if the file does not exist in the tarball. Directory write permission and free disk space equivalent to at least the size of the tarball will be needed.

      % ::tar::remove new.tar {file2 file3}
      % ::tar::contents new.tar
      file3

## Bugs, Ideas, Feedback

This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category tar of the Tcllib Trackers. Please also report any ideas for enhancements you may have for either package and/or documentation.

When proposing code changes, please provide unified diffs, i.e the output of diff -u.

Note further that attachments are strongly preferred over inlined patches. Attachments can be made by going to the Edit form of the ticket immediately after its creation, and then using the left-most button in the secondary navigation bar.

## Keywords

archive, tape archive, tar

## Category

File formats