a7d

This module is an implementation of archiver for a7d8473 archive format. It can archive directories, files, soft links, has shell interface.

What is a7d8473?

A7d8473 or simply a7d is a simple archive format, that has some nice features:

• If source directory has only text files, then archive will also be text file.
• Changing one line in the source file results in changing only one line in the archive.
• If all source files have line lenght limit, then archive will also have line lenght limit.
• Archived files are stored in compressor-friendly way: all the contents of the source file are usually included in the final archive file unchanged.
• Metadata is saved in git-like manner. Thus only this metadata is saved:
  • Executable flag.
  • Link flag.
• There is a bijection between the set of archive files and the set of directory structures.

Hello world

This is "Hello, world!" file pushed into a7d8473 archive.

a7d8473
:hello.txt/
Hello, world!
~ ~ ~

Here is a little more complex archive:

a7d8473
/name_of_directory/
:name_of_file.txt/
-> here is the content of file <-
~ ~ ~
!name_of_another_file_that_is_executable.py/
print('Hi')
~ ~ ~
@name_of_soft_link/
target_of_this_soft_link
~ ~ ~
@link_to_Hi.py/
./name_of_another_file_that_is_executable.py
~ ~ ~
/empty_directory/
\
\

The first line of archive file is always "a7d8473". Other lines describe archived files and directories. : before hello.txt means, that file hello.txt is neither executable nor soft link. There are other prefixes of file names:

• @ denotes soft links.
• ! denotes executable files.
• / denotes directories.
• : denotes simple files, which are neither executable nor soft links.

/ is also used as the end of the name because it is not a valid character in file names. \ means end of directory, while ~ ~ ~ denotes end of file content. Only printable ASCII characters are used outside of file contents. Thus, archive files are text files as long as source files are text files.