1) Its primary purpose is to take normal binary or text files and make them smaller in size. This saves great amounts of storage space, with typical results being approximately 1/4 to 1/3 of original size. It can handle any size file that can be placed on the disk, together with the compressed file it then makes. Files in excess of 1 Mb may be easily used, even though perhaps only 200 Kb RAM might be available.
This eliminates any potential problems from one computer to another.
It does this with by using special "compression tables." These are automatically built into the program and involve mathematical procedures which are simple for a computer.
2) The secondary purpose is to take more than one of these programs and include them in just one file, although each will have its own individual name inside that file.
This is called an "archive." In the days of CP/M, they were called "library" files. In the early days of MS-DOS (and other comparable programs used by IBM computers) they were called .ARC files.
However, as other comparable programs appeared, they were given various "extents" to identify the program used. Some sample names are .ARC, .DWC, .LZH, .PAK, .ZIP, .ZOO, etc.
Each has its own special characteristics.
Lists comparing the various programs are available.
ARCHIVE FILES
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LHA v2.11 can have hundreds of files in a single .LZH archive.
This allows storing complete hard disk directories in a space typically 1/2 or less the original total - although many of the files might already be archived.
One such check we tried, made a file we called "TEST.LZH." It had 200 files and was 41% the original directory size.
Not only is this a great saving in size for storage, but puts (in this case), the 200 files into one, single file. This is often beneficial. Among other things, all files associated with one program are kept together in the same archive.
1) To compress one file called ABC.TXT. (It will make a file called ABC.LZH.)
'a' LHA a ABC ABC.TXT or 'a' LHA a ABC.LZH ABC.TXT ^ ^ ^ a b c
a = command b = archive program name c = pgm (or pgms) to be added/compressed
Either is suitable, one requires more typing.
a) In this case, the "a" is called a command. There are 12 of those available (shown below). A few are duplicates to initially help users more familiar with other programs.
Typing LHA <ret> will display this list on the screen.
It also gives a very short summary what the command does.
2) ADDING a program to an existing file:
'a' LHA a ABC ABC.DOC ^ archive name
3) ADDING SEVERAL files at one time:
'a' LHA a ABC PGM1.EXT PGM2.EXT PGM3.EXT ^ archive name
4) DELETING a file called PGM4.EXT:
'd' LHA d ABC PGM4 ^ archive name
5) EXTRACTING a file called PGM4.EXT:
'e' (or 'x') LHA e ABC PGM4 ^ archive name
6) LOOKING at the archive contents:
'l' (or 'v') LHA l ABC PGM4 ^ archive name
7) MOVES files into archive and deletes file from directory:
'm' LHA m ABC PGM1 PGM2 PGM3 ^ archive name
8) DISPLAY a text file in an archive:
'p' LHA p ABC PGM4 ^ archive name
9) TEST the integrity of an archive:
't' LHA t ABC PGM4 ^ archive name
NOTE: LHA.EXE makes both "long and short SFX files." Check the advanced .DOC file for information.
It has a quite extensive discussion on the SFX files.
COMMANDS:
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There are 12 commands available.
The 'l' and 'v' are very slightly different, the 'v' putting the file name on a line by itself.) The 'e' and 'x' are slightly different, as well.
These are listed by typing just LHA without any command of file name:
<command> a: Add files u: Update files m: Move files f: Freshen files d: Delete files p: disPlay files e: Extract files x: eXtract files with pathnames l: List of files v: View listing of files with pathnames s: make a Self-extracting archive t: Test the integrity of an archive
OPTIONS
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There are 15 "options" which many users will not need/use.
They will be explained in detail in the LHA211.DOC manual for advanced users. Those are:
<option> r: Recursively collect files w: assign Work directory x: allow eXtended file names m: no Message for query p: distinguish full Path names c: skip time-stamp Check a: allow any Attributes of files z: Zero compression (only store) t: archive's Time-stamp option h: select Header level (default = 1) o: use Old compatible method n: display No indicator a/o pathname i: not Ignore lower case l: display Long name with indicator
