path: root/src/unalf.rst

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=====
unalf
=====

--------------------------------
extract Atari 8-bit ALF archives
--------------------------------

:Manual section: 1
:Manual group: Urchlay's Atari 8-bit Tools
:Date: |date|
:Version: |version|

SYNOPSIS
========

unalf [**--help**] [**-aehtklLopqtv**] [**-d** *dir*] [**-x** *wildcard*] *alf-file* [*wildcard* ...]

DESCRIPTION
===========

**unalf** lists or extracts the contents of an *ALF* archive.

*ALF* is a compressed archive format similar to **arc**\(1), though
not compatible with it. It was used on the Atari 8-bit platform
beginning in the late 1980s.

Extracted files are written to the current directory by
default. Existing files are backed up by default (by adding a **~**
suffix to the filename).

If one or more **wildcard** arguments are provided, files will only be
listed or extracted if they match one of the wildcards. See **WILDCARDS**
below for details.

OPTIONS
=======

-a
  Convert text file line endings and tabs from ATASCII to ASCII. Text
  files are detected by looking at the first 2 bytes of the extracted
  file. If both are printable ASCII (including ATASCII EOL, aka **$9B**), the
  file is considered text.

  Note that *only* line-endings and tabs are converted. Other ATASCII
  characters are left alone. If you need anything more in-depth, use
  **a8cat**\(1).

.. convert EOLs and tabs in text files.

**-aa**
  Convert line endings in all extracted files. This will corrupt any
  executables or non-text data files, so use with caution.

.. convert EOLs and tabs in ALL files.

-d output-dir
  Write extracted files to this directory, which will be created if it
  does not exist. The default is the current directory.

.. set output directory (created if needed).

-e
  Extract files. This is actually a no-op, as extraction is the
  default action.

.. extract files (redundant; this is the default action).

-h, --help
   Show built-in help message.

.. show this help message.

-k
  Keep trailing periods. In most (all?) ALF files, filenames that have no
  extension are stored with a trailing period, e.g. '**FOO**' would
  be stored as '**FOO.**'. On the Atari, the extracted file would be
  named '**FOO**', so **unalf** does the same by default. With **-k**,
  the file will be named '**FOO.**'.

.. keep trailing periods (dots) in filenames.

-l
  List filenames in archive, one per line, but do not extract. Use
  **-v** for more information (file size, etc). Obeys *wildcards* and
  the **-x**, **-L**, **-k** options.

.. list files in archive (filenames only).

-L
  Lowercase filesnames. Example: **FOO.TXT** will extract to **foo.txt**.

.. use lowercase filenames.

-o
  Overwrite files, if they already exist. The default is to rename
  existing files, adding a **~** suffix. Note that renaming **file**
  to **file~** *will* overwrite **file~** if it already exists.

.. overwrite files (do not create file~ backups).

-p
  Extract to standard output. All the files that get extracted will be
  printed to stdout with no delimiters, so this is most useful when
  only extracting one file. **-q** is automatically enabled by this option.

  *Warning:* No checking is done to see whether stdout is a terminal.
  Printing binary files to a terminal is a good way to make a mess.
  Even text files with the EOLs translated can still contain ATASCII
  formatting/graphics codes that can confuse your terminal. You have
  been warned.

.. extract to stdout (enables -q).

-q
  Quiet extraction or testing: do not print "Uncrunching *file*"
  or "Testing *file*" messages. Errors and warnings will still be
  printed. This is the default when **-p** is used. This option
  doesn't do anything when used with **-l** or **-v**.

.. quiet: don't print filenames during extraction/testing.

-t
  Test archive. Same as extraction, except the files are not written
  anywhere.

.. test archive.

-v
  Verbose listing of archive contents, with compressed and original
  sizes, compression ration, date/time stamps, and checksum. The
  output format is similar to that of **arc -v**, minus the *Stowage*
  column, since *ALF* doesn't support multiple compression types. The
  date and time are displayed, but in most .alf files these are the
  default values of "8 Jan 82  12:24a".

  Unlike **-l**, the **-v** listing shows the filenames exactly as
  stored in the archive (ignores **-L**, enables **-k**), and always
  shows all the files (ignores *wildcards* and **-x**).

.. verbose listing of archive contents.

-V, --version
  Show **unalf** version number and exit.

.. show version number.

-x wildcard
  Exclude (do not list or extract) files matching *wildcard*. See
  **WILDCARDS** below. This option can be given multiple times
  to exclude multiple patterns.

.. exclude <wildcard>. may be given multiple times.

WILDCARDS
=========

Wildcard (aka glob) matching works like it does on the Atari: *\*.\**
matches any filename (whether or not it has an extension), and *\**
or *\*.* only match filenames with no extension.

A *\** matches any number of characters (including zero). A *?*
matches a single character.

Like the Atari, anything in the name or extension following a *\** is
ignored: **FOO\*BAR.TXT** is equivalent to **FOO\*.TXT**, and
**FOO.T\*T** is equivalent to **FOO.T\***. **FOO\*TXT** is
equivalent to **FOO\***, and *will not* match the file **FOO.TXT**.

Unlike the Atari, matching is case-insensitive.

To avoid your shell trying to expand the wildcards, always quote them!
Example::

  unalf filename.alf '*.txt'

EXIT STATUS
===========

0
  Success.

1
  Fatal error (I/O or bad command-line arguments, stack under/overrun).

2
  Processing completed OK, but at least one file in the archive
  has a bad checksum.

DIAGNOSTICS
===========

Besides the standard error messages such as "no such file or directory":

**this is an ARC file, not ALF**
  Self-explanatory. Use the **arc**\(1) utility for this file.

**not an ALF file**
  Self-explanatory. Either the file is too small (less than 29 bytes)
  or its first two bytes don't match the *ALF* signature **0x1a** **0x0f**\.

**junk at EOF (ignored)**
  Usually this is caused by the .alf file being stored on a CP/M disk
  at some time, or by a dumb file transfer protocol. Either way, the
  file gets padded to the block size of the filesystem or protocol.
  Usually, the padding characters are **0x1a**, aka ASCII control-Z.

  If you see this message, you can ignore it. It's intended to let
  you know that this .alf file can't be appended to by the **ALF.COM**
  aka **LZ.COM** Atari utility.

**checksum error on** *<file>*
  The archive is corrupt. If *<file>* is a text file, it may be
  partially readable. If it's an executable or other binary file, it's
  probably unrecoverable.

**stack underrun/overrun**
  Generally means the archive is corrupt. Valid ALF files should never
  cause these errors.

  If you have an ALF file that does this, try it with the Atari
  **UNALF14.COM** and see if it has the same problem. If it doesn't,
  you've found a bug in **unalf**, please send me the .alf file via
  email (see **AUTHOR**, below). Actually, I'd be interested to see
  the .alf file even if it doesn't work on the Atari either.

**bad Atari filename** *<filename>* *<reason>*
  The filename stored in the ALF header doesn't follow the rules for
  Atari DOS filenames. *<reason>* will be something like "doesn't start
  with A-Z" or "invalid character". The filename will be printed with
  any unprintable characters as hex values (e.g. **$01**).

**header #<n> (compressed|original) size is...**
  Followed by "impossibly large", "suspiciously large", or "too large
  to fit on a floppy disk". May indicate a corrupt archive, or someone
  really might have created an ALF file with files this big... though
  "impossibly large" means >=16MB. **unalf** can't extract a file
  that big.

**filename has underscore, OK on Sparta/MyDOS, not Atari DOS 2.x**
  Not an actual problem, unless you try to extract this ALF file on
  an Atari running Atari DOS 2.0/2.5, or any other DOS that doesn't
  allow underscores in filenames.

NOTES
=====

This **unalf** is 100% compatible with the original Atari **UNALF14.COM**
aka **DZ.COM**, with the following differences:

- There is no interactive mode. The file to extract must be given as
  a command-line argument, and the output directory must be given
  with the **-d** option.

- This **unalf** is capable of listing or testing the contents of an archive
  without extracting it, plus other handy features such as extracting
  to standard output and text file EOL conversion.

- Turning the screen off for speed makes no sense on modern operating
  systems, so there's no option for that.

Neither this **unalf** nor **UNALF14.COM** actually use the dates/times
stored in the archive. Extracted files will have their timestamps set
to the current date/time.

COPYRIGHT
=========

**unalf** is released under the WTPFL: Do WTF you want with this.

AUTHOR
======

B. Watson <urchlay@slackware.uk>

SEE ALSO
========

**unalf**\(1)

.. include:: manftr.rst