Description 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 magic bytes, not by the file name extension. These utilities are not wrapper scripts but safer and more efficient C++ programs. In particular the option '--recursive' 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, 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. 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 FORMAT NOTE 2: The standard POSIX compress format (.Z) is obsolete and is only supported through gzip.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. Copyright (C) 2009-2023 Antonio Diaz Diaz. This file is free documentation: you have unlimited permission to copy, distribute, and modify it. The file Makefile.in is a data file used by configure to produce the Makefile. It has the same copyright owner and permissions that configure itself.