Zutils is a collection of utilities able to process any combination of compressed and uncompressed files transparently. If any file given, including standard input, is compressed, its decompressed content is used. Compressed files are decompressed on the fly; no temporary files are created. Data format is detected by its identifier string (magic bytes), not by the file name extension. Empty files are considered uncompressed.
These utilities are not wrapper scripts but safer and more efficient C++ programs. In particular the option '--recursive' is efficient in those utilities supporting it.
The utilities provided are:
zcat - Decompresses and copies files to standard output.
zcmp - Decompresses and compares two files byte by byte.
zdiff - Decompresses and compares two files line by line.
zgrep - Decompresses and searches files for a regular expression.
ztest - Tests integrity of compressed files.
zupdate - Recompresses files to lzip format.
The formats supported are bzip2, gzip,
lzip, xz, and zstd.
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.
To install zutils along with GNU gzip and keep the gzip scripts, the recommended method is to rename the gzip scripts and man pages to 'gzcat', 'gzcat.1', etc, by configuring gzip as follows:
./configure --program-transform-name='s/^z/gz/'
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. Zstd currently does not even document its exit status in its man page.
FORMAT NOTE 1: The option '--format' allows the processing of a subset of formats in recursive mode and when trying compressed file names. For example, use the following command to search for the string 'foo' in gzip and lzip files only: "zgrep foo -r --format=gz,lz somedir somefile.tar".
FORMAT NOTE 2: The standard POSIX compress format (.Z) is obsolete and is only supported through gzip. For this to work, the gzip program used (for example GNU gzip) must be able to decompress .Z files.
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.
The manual is available in the info system of the GNU Operating System. Use info to access the top level info page. Use info zutils to access the zutils section directly.
An online manual for zutils can be found at manual/zutils_manual.html.
The latest released version of zutils can be found at http://download.savannah.gnu.org/releases/zutils/. You may also subscribe to zutils-bug and receive an email every time a new version is released.
To decompress zutils tarballs you may need lzip from
http://www.nongnu.org/lzip/lzip.html.
Then use "tar -xf zutils[version].tar.lz" or
"lzip -cd zutils[version].tar.lz | tar -xf -"
to extract the files.
For general discussion of errors (bugs) in zutils the mailing list zutils-bug@nongnu.org is the most appropriate forum. Please send messages as plain text. Do not send HTML, base64 MIME, nor multiple formats. Use a descriptive subject line with the word "zutils" in it.
An archive of the bug report mailing list is available at http://lists.gnu.org/mailman/listinfo/zutils-bug.
To contact the author, either to report an error (bug) or to contribute fixes or improvements, send mail to zutils-bug@nongnu.org. Please send messages as plain text. If posting patches they should be in unified diff format against the latest version. They should include a text description.
If you know someone who is using gzip, bzip2, or xz, please tell him/her about the advantages of switching to lzip. See this comparison of the formats and this comparison of the tools.
See also the zutils project page at Savannah.
Zutils is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version.
Copyright © 2024 Antonio Diaz Diaz
You are free to copy, modify, and distribute all or part of this article without limitation.
Updated: 2024-12-09
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