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ZTEST(1) User Commands ZTEST(1)


ztest - verify the integrity of compressed files


ztest [options] [files]


ztest verifies the integrity of the compressed files specified. It also warns if an uncompressed file has a compressed file name extension, or if a compressed file has a wrong compressed extension. Uncompressed files are otherwise ignored. If a file is specified as '-', the integrity of compressed data read from standard input is verified. Data read from standard input must be all in the same compressed format. If a file fails to decompress, does not exist, can't be opened, or is a terminal, ztest continues verifying the rest of the files. A final diagnostic is shown at verbosity level 1 or higher if any file fails the test when testing multiple files.

If no files are specified, recursive searches examine the current working directory, and nonrecursive searches read standard input.

The formats supported are bzip2, gzip, lzip, xz, and zstd.

Note that error detection in the xz format is broken. First, some xz files lack integrity information. Second, not all xz decompressors can verify the integrity of all xz files. Third, section 'Stream Flags' of the xz format specification allows xz decompressors to produce garbage output without issuing any warning. Therefore, xz files can't always be verified as reliably as files in the other formats can.

Exit status is 0 if all compressed files verify OK, 1 if environmental problems (file not found, invalid command line options, I/O errors, etc), 2 if any compressed file is corrupt or invalid, or if any file has an incorrect file name extension.


display this help and exit
output version information and exit
process only the formats in <list>
don't read runtime configuration file
force the input format
suppress all messages
operate recursively on directories
recursively follow symbolic links
be verbose (a 2nd -v gives more)
set compressor and options for bzip2 format
set compressor and options for gzip format
set compressor and options for lzip format
set compressor and options for xz format
set compressor and options for zstd format

Valid formats for options '-M' and '-O' are 'bz2', 'gz', 'lz', 'xz', and 'zst'.


Report bugs to
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Copyright © 2023 Antonio Diaz Diaz. License GPLv2+: GNU GPL version 2 or later <>
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.


The full documentation for ztest is maintained as a Texinfo manual. If the info and ztest programs are properly installed at your site, the command

info zutils

should give you access to the complete manual.

January 2023 zutils 1.12