PCMANAGE and DCOMPRES Documentation file

UTILITIES  
Vol. 8, No. 21

Ross M. Greenberg 
December 12, 1989 (Utilities)

Purpose: To provide automatic compression of infrequently accessed files and 
         automatic decompression when they are called.  The user can set the 
         inactive period necessary before a file is compressed, can restrict 
         the drive and/or path of operation, and can specifically exclude 
         named files or directories.

Format: DCOMPRES [/i] [/An]
	
Remarks: DCOMPRES is a memory-resident program that should be loaded from an 
         AUTOEXEC.BAT file.  In each subdirectory it creates and maintains a 
         file called INDEX.CMP.  This file stores the date and time each file 
         was last accessed and whether the file is compressed or not.  When a 
         compressed file is called, DCOMPRES decompresses it automatically.

	INDEX.CMP files are normally created with a Read-Only file attribute,
        as they should never be deleted while any compressed files remain in 
        the directory.  To remove a directory requires changing this file 
        attribute with the DOS ATTRIB command (for DOS 3.x) or with a utility 
        such as ATTR.COM (PC Magazine, June 10, 1986).  INDEX.CMP files can be 
        created with other attributes by loading DCOMPRES with its optional 
        /An switch, where n has one of the following values:  0 (visible, 
        read-write); 1 (hidden, read-write); 2 (visible, read-only--the 
        default); or 3 (hidden, read-only).

	If an INDEX.CMP file is accidentally deleted or damaged, all compressed
        files in a directory can be restored by loading DCOMPRES with its 
        optional /i switch parameter and issuing a command such as COPY *.* 
        NUL.

Format:	PCMANAGE [/i] [/dn] [/cn] [/bn] [/pd]

Remarks: When invoked with its default settings, PCMANAGE compresses all files
         on drive C: (including those in all subdirectories) that have not been
         accessed in 7 days and whose compression will save at least 10 percent
         in file length and 2,048 bytes (nominally one cluster).  The user can
         change the number of days before compression by employing the optional 
         /dn switch with values from 1 to 32767 for n.  Similarly, the optional
         /cn switch sets the minimum acceptable compression percentage and 
         accepts any n value of 5 or greater.  The /bn switch sets the number
         of bytes in one disk cluster (the minimum real saving possible); it 
         accepts values from 1024 to 32767 for n.

	The optional /pd switch, with an appropriate drive letter (and/or path)
        entered for d, allows PCMANAGE to be used on drives other than C: and 
        permits restricting its operations to the files along a specific path 
        (and its subdirectories).

	The /i switch is used with PCMANAGE when installing the utility.  This
        should not be done until after you have prepared any necessary 
        DCOMPRES.EXL (exclude) file, as described in the Notes below.  That 
        done, and with DCOMPRES loaded, use the DOS DATE command to set the 
        current date back by at least one week.  Then enter PCMANAGE /i, which 
        will cause it to examine all files on drive C: (or as modified by the
        /pn switch).  Use the DATE command to reset the present date and run 
        PCMANAGE again, without the /i parameter.  All files on the drive 
        except those excluded by DCOMPRES.EXL or the optional /pn switch will
        now be compressed initially, if warranted by the disk space savings. 
        The files will be decompressed as soon as accessed, and programs called
        frequently will not be compressed again.  

	Running PCMANAGE weekly will automatically cause files that have become
        stale-dated to be compressed.

Note 1:	Up to 100 files or directories (and child directories below them) can
        be excluded from possible compression by PCMANAGE.  All OS/2 files and
        copy-protected software should be so excluded.  To do so, create a 
        pure ASCII file called DCOMPRES.EXL in the root directory of drive C:. 
        List one entry per line.  To exclude all files that have a .SYS 
        extension and all files in and under an OS2 directory on drive C:, the
        DCOMPRES.EXL file would have two entries:
	
	*.SYS
	C:\OS2\*

Note 2:	DCOMPRES and PCMANAGE can handle a maximum of 100 files per directory.
        Files in excess of this number will not be harmed, but will not be 
        processed.

Note 3: DCOMPRES should be installed in the AUTOEXEC.BAT file before any 
        anti-virus software.  Anti-virus software that uses checksumming 
        procedures that cannot be disabled until program execution time is 
        incompatible with DCOMPRES.