zutils/README

Description

Zutils is a collection of utilities able to process any combination of
compressed and uncompressed files transparently. If any given file,
including standard input, is compressed, its decompressed content is
used. Compressed files are decompressed on the fly; no temporary files
are created.

These utilities are not wrapper scripts but safer and more efficient C++
programs. In particular the '--recursive' option is very efficient in
those utilities supporting it.

The utilities provided are zcat, zcmp, zdiff, zgrep, ztest and zupdate.
The formats supported are bzip2, gzip, lzip and xz.
Zutils uses external compressors. The compressor to be used for each
format is configurable at runtime.

zcat, zcmp, zdiff, and zgrep are improved replacements for the shell
scripts provided by GNU gzip. ztest is unique to zutils. zupdate is
similar to gzip's znew.

NOTE: Bzip2 and lzip provide well-defined values of exit status, which
makes them safe to use with zutils. Gzip and xz may return ambiguous
warning values, making them less reliable back ends for zutils.

FORMAT NOTE 1: The '--format' option allows the processing of a subset
of formats in recursive mode and when trying compressed file names:
'zgrep foo -r --format=bz2,lz somedir somefile.tar'.

FORMAT NOTE 2: If the '--force-format' option is given, the files are
passed to the corresponding decompressor without verifying their format,
allowing for example the processing of compress'd (.Z) files with gzip:
'zcmp --force-format=gz file.Z file.lz'.

LANGUAGE NOTE: Uncompressed = not compressed = plain data; it may never
have been compressed. Decompressed is used to refer to data which have
undergone the process of decompression.


Copyright (C) 2009-2019 Antonio Diaz Diaz.

This file is free documentation: you have unlimited permission to copy,
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