ar archives

[Daniel Brumbaugh Keeney]

Is there cross-platform way of extracting or creating `ar' archives?


Daniel Brumbaugh Keeney

 

[Eric Hodel]

Is there cross-platform way of extracting or creating `ar' archives?

ar(5) on my system says this:

A file created with ar begins with the ``magic'' string "!<arch>
\n". The rest of the archive is made up of objects, each of which
is composed of a header for a file, a possible file name, and the
file contents. The header is portable between machine
architectures, and, if the file contents are printable, the archive
is itself printable.

and proceeds to describe the latest version of the format which fits
in about 26 lines. It should be really easy.

It makes a note at the bottom of the magic strings for older versions
of ar, but these are probably ancient.

 

[Thomas Hurst]

[answer, which from a Mac user might only apply to BSD ar?]

Speaking of archive handling, a nice project for someone might be a Ruby
interface to BSD's libarchive[1], which would provide instant support
for tarballs of many different formats, cpio, pax, BSD/GNU ar, write
support for shar and read support for ISO images and zip archives, as
well as transparent gz/bz2/z handling. There's a Win32[2] port too.

1: http://people.freebsd.org/~kientzle/libarchive/
2: http://gnuwin32.sourceforge.net/packages/libarchive.htm