Category : C Source Code
Archive   : PORTABLC.ZIP
Filename : SPLIT_F.DOC

SPLIT

written by Charlie Beerman
July 12, 1986


SPLIT has been written using the Lattice C compiler,
version 2.0, on an AT&T 6300 with MS-DOS 2.11. It is hereby
placed in the public domain, with no warranties express or
implied.

The purpose of SPLIT is to split a large file (text or
binary) into a series of smaller files, and then to recombine
those component files back into an exact copy of the original.
This is useful for several purposes, among which are the storage
of a very large file ( > 360K ) on several floppy disks, or the
piecewise transfer of a large file over a communications line.
The latter has been my motivation for writing this program. I
suffer from a noisy phone line, and find that in trying to
transfer large files I get halfway (not even) done and a glitch
in the line trashes the transfer. I figure I can successfully
transfer a file in several small pieces and provide a utility
for recombining it.

SPLIT is fairly easy to use. There are three main usages:

1.) Split a file into components of specified size.
2.) Split a file into a specified number of
components.
3.) Recombine a file from its components.


1.) Splitting a file into components of specified size:

Enter the command

SPLIT S Ki File_to_split Component_prefix

Where
i is the desired size in KILOBYTES of the components.
File_to_split is the file to be divided.
Component_prefix is the filename (without extension)
of the components.

The program will display a summary of the file size of the
file to be split, the specified component file size, and
the number of files it will create. It also displays the
name and size of each file it creates. (Note that the last
file may be smaller than the others.) The files created
are named by taking the specified Component prefix and
appending the extension

.-nn

to the filename. The nn in the component file is
sequentially numbered for each component file created.
Thus, if the source file has 50K bytes and the maximum
component filesize is 25K bytes, and the specified prefix
is "PREFIX", then two files will be created with names

PREFIX.-01 and
PREFIX.-02

At the completion of the process the total size of
the components is displayed as a check for successful
execution.

2.) Splitting a file into a specified number of files:

Enter the command

SPLIT S Ni File_to_split Component_prefix

Where
i is the number of components to create.
all the rest of the arguments are the same as above.

The component files will all be of equal size (except
perhaps the last one), and will be named in the same way as
above. The same summary information is displayed as
processing occurs.


3.) Combining components into a single file:

Enter the command

SPLIT C File_to_create Component_list


Where
File_to_create is the sum of the components
Component_list is a list of files to combine in the
specified order. Filenames are separated by
spaces.

This will combine the files in the component list into the
specified create file. The created file may not have the
same name as any of the component files. The names of the
files are displayed as they are added to the created file.


4.) Notes, Restrictions and Errors:

A maximum of 99 component files can be created for each
split. An error message will be issued if you ask for more
than 99 files or ask for such a small component size that
more than 99 files would have to be created.

You may not split files into components of less than
4 Kilobytes. Again, the program will tell you if you try
to do this.

Arguments may be entered in upper or lower case, and should
be separated by spaces. There should NOT be a space
between the "K" or "N" and the number which follows it.
The program checks for the proper number and type of
arguments as much as it can.

The filenames may include drive and/or path specifiers.
They may NOT include wildcards (* or ?).

The program will tell you if it cannot open, read from, or
write to a file. Common causes of such errors are a
mistyped filename, a missing file, or a write-protected or
full disk.

Any files which already exist when the program tries to
create them will be destroyed before being created.

Some of the error messages refer to component files as
"section files".