MPE/iX Shell and Utilities Reference Manual, Vol 2

pack(1) MPE/iX Shell and Utilities pack(1)
NAME
pack — compress files by Huffman encoding
SYNOPSIS
pack [[][–f][–o file] file] ...
DESCRIPTION
pack compresses argument files using a Huffman minimal redundancy code on a byte basis.
By default, each file is compressed in place, and the resulting file has a .z extension
appended to the file name, but keeps the same owner and permissions. For example, abc is
compressed into abc.z. The times of last access and last modification are also preserved.
Packed files can be identified by file(1) and uncompressed by unpack(1) (which unpacks
the file in place) or pcat(1) (which unpacks to the standard output).
Normally pack reports the degree of compression achieved in each file (the report is printed
on the standard output). This number can be negative for small files with little redundancy if
the –f option is used.
pack accepts the following options:
displays more detail on size, overhead, and entropy (information rate). This option
can be used several times on the command line, and acts as a toggle, inverting the
detailed-report flag at each mention.
–f forces compression when it normally does not occur. Without this option, pack does
not compress a file if its size is not reduced by compression; the file is already com-
pressed; or the file has more than one link.
–o file specifies a different output file, so that compressed output is written to file rather than
overwriting the original input file. Several input and output files may be specified.
For example,
pack -o out1 in1 -o out2 in2
packs file in1 into out1 and file in2 into out2. The input files are not changed.
FILES
pk$ Temporary copy of input.
Note: This is stored under the current directory rather than the directory given by
TMPDIR
.
1-402 Commands and Utilities