compact(1)						      General Commands Manual							compact(1)

NAME

       compact, uncompact, ccat - compact and uncompact files, and cat them

SYNOPSIS

       [sfile] ...

       [cfile] ...

       [cfile] ...

DESCRIPTION

       compresses  the	named files using an adaptive Huffman code.  If no file names are given, standard input is compacted and sent to the stan-
       dard output.  operates as an on-line algorithm.	Each time a byte is read, it is encoded immediately according to the current prefix  code.
       This  code  is an optimal Huffman code for the set of frequencies seen so far.  It is unnecessary to attach a decoding tree in front of the
       compressed file because the encoder and the decoder start in the same state and stay synchronized.  Furthermore, and can  operate  as  fil-
       ters.  In particular,

       operates as a (very slow) no-op.

       When  an  argument  file  is given, it is compacted, the resulting file is placed in and file is unlinked.  The first two bytes of the com-
       pacted file code the fact that the file is compacted.  These bytes are used to prohibit recompaction.

       The amount of compression to be expected depends on the type of file being compressed.  Typical file size reduction  (in  percent)  through
       compression are: Text, 38%; Pascal Source, 43%; C Source, 36%; and Binary, 19%.

       restores the original file from a file compressed by If no file names are specified, standard input is uncompacted and sent to the standard
       output.

       writes the specified c_file, compressed by to standard output, without uncompressing the file.

   Operands
       The commands recognize the following operands:

	      cfile	Compacted file.

	      sfile	Source file to compact or uncompact.  If no file names are given, the commands use standard input and sent to the standard
			output.  places the compacted file in

   Access Control Lists (ACLs)
       On systems that implement access control lists, when a new file is created with the effective user and group ID of the caller, the original
       file's ACL is copied to the new file after being altered to reflect any change in ownership (see acl(5) and aclv(5)).  In JFS file systems,
       files  created  by or do not inherit their parent directory's default ACL entries (if any), but instead retain their original ACLs.  When a
       file being compacted or uncompacted resides on a JFS file system, and the compacted or uncompacted file resides on an HFS file  system  (or
       vice versa), as the result of or the use of or as a filter, optional ACL entries are lost.

WARNINGS

       On short-file-name systems, the last segment of the file name must contain 12 or fewer characters to allow space for the appended

DEPENDENCIES

   NFS
       Access control list entries of networked files are summarized (as returned in by but not copied to the new file (see stat(2)).

AUTHOR

       was developed by Colin L. Mc Master.

FILES

       compacted file created by compact, removed by uncompact

SEE ALSO

       compress(1), pack(1), acl(5), aclv(5).

       Gallager, Robert G., "Variations on a Theme of Huffman," vol. IT-24, no. 6, November 1978, pp. 668 - 674.

																	compact(1)