My client is a big user of the "compress" utility on Solaris 2.8; they use this in preference to gzip for some wierd reason.
The client has housekeeper scripts that compress log files nightly. I have a need to access the logs (uncompressed) from some perl scripts. I am looking for a module which understands this compression format.
I have tried Compress::Zlib and Compress:LZF, both in vain. Is there a module out there that will do the trick? The documentation on "compress" is scant to say the least:
User Commands compress(1)
NAME
compress, uncompress, zcat - compress, uncompress files or
display expanded files
SYNOPSIS
compress [ -fv ] [ -b bits ] [ file ... ]
compress [ -cfv ] [ -b bits ] [ file ]
uncompress [ -cfv ] [ file ... ]
zcat [ file ... ]
DESCRIPTION
compress
The compress utility will attempt to reduce the size of the
named files by using adaptive Lempel-Ziv coding. Except when
the output is to the standard output, each file will be
replaced by one with the extension .Z, while keeping the
same ownership modes, change times and modification times.
If appending the .Z to the file pathname would make the
pathname exceed 1023 bytes, the command will fail. If no
files are specified, the standard input will be compressed
to the standard output.
The amount of compression obtained depends on the size of
the input, the number of bits per code, and the distribution
of common substrings. Typically, text such as source code or
English is reduced by 50-60%. Compression is generally much
better than that achieved by Huffman coding (as used in
pack(1)), and takes less time to compute. The bits parameter
specified during compression is encoded within the
compressed file, along with a magic number to ensure that
neither decompression of random data nor recompression of
compressed data is subsequently allowed.
uncompress
The uncompress utility will restore files to their original
state after they have been compressed using the compress
utility. If no files are specified, the standard input will
be uncompressed to the standard output.
This utility supports the uncompressing of any files pro-
duced by compress. For files produced by compress on other
systems, uncompress supports 9- to 16-bit compression (see
-b).
zcat
The zcat utility will write to standard output the
uncompressed form of files that have been compressed using
compress. It is the equivalent of uncompress -c. Input files
are not affected.
SunOS 5.8 Last change: 9 Sep 1999 1
User Commands compress(1)
OPTIONS
The following options are supported:
-c Write to the standard output; no files are
changed and no .Z files are created. The behavior
of zcat is identical to that of `uncompress -c'.
-f When compressing, force compression of file, even
if it does not actually reduce the size of the
file, or if the corresponding file.Z file already
exists. If the -f option is not given, and the
process is not running in the background, prompt
to verify whether an existing file.Z file should
be overwritten. When uncompressing, do not prompt
for overwriting files. If the -f option is not
given, and the process is not running in the
background, prompt to verify whether an existing
file should be overwritten. If the standard input
is not a terminal and -f is not given, write a
diagnostic message to standard error and exit
with a status greater than 0.
-v Verbose. Write to standard error messages con-
cerning the percentage reduction or expansion of
each file.
-b bits
Set the upper limit (in bits) for common sub-
string codes. bits must be between 9 and 16 (16
is the default). Lowering the number of bits will
result in larger, less compressed files.
OPERANDS
The following operands are supported:
file A path name of a file to be compressed. If file
is -, or if no file is specified, the standard
input will be used.
USAGE
See largefile(5) for the description of the behavior of
compress, uncompress, and zcat when encountering files
greater than or equal to 2 Gbyte ( 2**31 bytes).
ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment
variables that affect the execution of compress, uncompress,
and zcat: LC_CTYPE, LC_MESSAGES, and NLSPATH.
SunOS 5.8 Last change: 9 Sep 1999 2
User Commands compress(1)
EXIT STATUS
The following error values are returned:
0 Successful completion.
1 An error occurred.
2 One or more files were not compressed because they
would have increased in size (and the -f option was
not specified).
>2 An error occurred.
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWesu |
|_____________________________|_____________________________|
| CSI | Enabled |
|_____________________________|_____________________________|
SEE ALSO
ln(1), pack(1), attributes(5), environ(5), largefile(5)
DIAGNOSTICS
Usage: compress -fvc -b maxbits file...
Invalid options were specified on the command line.
Missing maxbits
Maxbits must follow -b, or invalid maxbits, not a
numeric value.
file: not in compressed format
The file specified to uncompress has not been
compressed.
file: compressed with xxbits, can only handle yybits
file was compressed by a program that could deal with
more bits than the compress code on this machine.
Recompress the file with smaller bits.
file: already has .Z suffix -- no change
The file is assumed to be already compressed. Rename
the file and try again.
file: already exists; do you wish to overwrite (y or n)?
Respond y if you want the output file to be replaced;
SunOS 5.8 Last change: 9 Sep 1999 3
User Commands compress(1)
n if not.
uncompress: corrupt input
A SIGSEGV violation was detected, which usually means
that the input file is corrupted.
Compression: xx.xx%
Percentage of the input saved by compression.
(Relevant only for -v.)
- - not a regular file: unchanged
When the input file is not a regular file, (such as a
directory), it is left unaltered.
- - has xx other links: unchanged
The input file has links; it is left unchanged. See
ln(1) for more information.
- - file unchanged
No savings are achieved by compression. The input
remains uncompressed.
filename too long to tack on .Z
The path name is too long to append the .Z suffix.
NOTES
Although compressed files are compatible between machines
with large memory, -b 12 should be used for file transfer to
architectures with a small process data space (64KB or
less).
compress should be more flexible about the existence of the
.Z suffix.
--
I'm Not Just Another Perl Hacker
In reply to Wanted: perl equivalent of Solaris compress utility by rinceWind
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