\input texinfo @c -*-texinfo-*- @c %**start of header @setfilename zutils.info @documentencoding ISO-8859-15 @settitle Zutils Manual @finalout @c %**end of header @set UPDATED 7 January 2023 @set VERSION 1.12 @dircategory Compression @direntry * Zutils: (zutils). Utilities dealing with compressed files @end direntry @ifnothtml @titlepage @title Zutils @subtitle Utilities dealing with compressed files @subtitle for Zutils version @value{VERSION}, @value{UPDATED} @author by Antonio Diaz Diaz @page @vskip 0pt plus 1filll @end titlepage @contents @end ifnothtml @ifnottex @node Top @top This manual is for Zutils (version @value{VERSION}, @value{UPDATED}). @menu * Introduction:: Purpose and features of zutils * Common options:: Options common to all utilities * Configuration:: The configuration file zutils.conf * Zcat:: Concatenating compressed files * Zcmp:: Comparing compressed files byte by byte * Zdiff:: Comparing compressed files line by line * Zgrep:: Searching inside compressed files * Ztest:: Testing the integrity of compressed files * Zupdate:: Recompressing files to lzip format * Problems:: Reporting bugs * Concept index:: Index of concepts @end menu @sp 1 Copyright @copyright{} 2009-2023 Antonio Diaz Diaz. This manual is free documentation: you have unlimited permission to copy, distribute, and modify it. @end ifnottex @node Introduction @chapter Introduction @cindex introduction @uref{http://www.nongnu.org/zutils/zutils.html,,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 @option{--recursive} is very efficient in those utilities supporting it. @noindent The utilities provided are @command{zcat}, @command{zcmp}, @command{zdiff}, @command{zgrep}, @command{ztest}, and @command{zupdate}.@* The formats supported are bzip2, gzip, @uref{http://www.nongnu.org/lzip/lzip.html,,lzip}, xz, and zstd.@* Zutils uses external compressors. The compressor to be used for each format is configurable at runtime. @command{zcat}, @command{zcmp}, @command{zdiff}, and @command{zgrep} are improved replacements for the shell scripts provided by GNU gzip. @command{ztest} is unique to zutils. @command{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. @xref{compressor-requirements}. FORMAT NOTE 1: The option @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 @samp{foo} in gzip and lzip files only: @w{@samp{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. @sp 1 Numbers given as arguments to options (positions, sizes) may be followed by a multiplier and an optional @samp{B} for "byte". Table of SI and binary prefixes (unit multipliers): @multitable {Prefix} {kilobyte (10^3 = 1000)} {|} {Prefix} {kibibyte (2^10 = 1024)} @item Prefix @tab Value @tab | @tab Prefix @tab Value @item k @tab kilobyte (10^3 = 1000) @tab | @tab Ki @tab kibibyte (2^10 = 1024) @item M @tab megabyte (10^6) @tab | @tab Mi @tab mebibyte (2^20) @item G @tab gigabyte (10^9) @tab | @tab Gi @tab gibibyte (2^30) @item T @tab terabyte (10^12) @tab | @tab Ti @tab tebibyte (2^40) @item P @tab petabyte (10^15) @tab | @tab Pi @tab pebibyte (2^50) @item E @tab exabyte (10^18) @tab | @tab Ei @tab exbibyte (2^60) @item Z @tab zettabyte (10^21) @tab | @tab Zi @tab zebibyte (2^70) @item Y @tab yottabyte (10^24) @tab | @tab Yi @tab yobibyte (2^80) @end multitable @node Common options @chapter Common options @cindex common options The following @uref{http://www.nongnu.org/arg-parser/manual/arg_parser_manual.html#Argument-syntax,,options}: are available in all the utilities. Rather than writing identical descriptions for each of the programs, they are described here. @ifnothtml @xref{Argument syntax,,,arg_parser}. @end ifnothtml @table @code @item -h @itemx --help Print an informative help message describing the options and exit. @command{zgrep} only supports the @option{--help} form of this option. @anchor{version} @item -V @itemx --version Print the version number on the standard output and exit. This version number should be included in all bug reports. In verbose mode, @command{zdiff} and @command{zgrep} print also the version of the diff or grep program used respectively. At verbosity level 1 (2 for @command{zdiff} and @command{zgrep}) or higher, print also the versions of the compressors used (perhaps limited by option @option{--format}). (The compressors used must support the option @option{-V} for this to work). @item -M @var{format_list} @itemx --format=@var{format_list} Process only the formats listed in the comma-separated @var{format_list}. Valid formats are @samp{bz2}, @samp{gz}, @samp{lz}, @samp{xz}, @samp{zst}, and @samp{un} for @samp{uncompressed}, meaning "any file name without a known extension". This option excludes files based on extension, instead of format, because it is more efficient. The exclusion only applies to names generated automatically (for example when adding extensions to a file name or when operating recursively on directories). Files given in the command line are always processed. Each format in @var{format_list} enables file names with the following extensions: @multitable {bz2} {enables} {any other file name} @item bz2 @tab enables @tab .bz2 .tbz .tbz2 @item gz @tab enables @tab .gz .tgz .Z @item lz @tab enables @tab .lz .tlz @item xz @tab enables @tab .xz .txz @item zst @tab enables @tab .zst .tzst @item un @tab enables @tab any other file name @end multitable @item -N @itemx --no-rcfile Don't read the runtime configuration file @file{zutils.conf}. @item --bz2=@var{command} @itemx --gz=@var{command} @itemx --lz=@var{command} @itemx --xz=@var{command} @itemx --zst=@var{command} Set program to be used as decompressor for the corresponding format. @var{command} may include arguments. For example @w{@option{--lz='plzip --threads=2'}}. @command{zupdate} uses @option{--lz} for compression, not for decompression (@pxref{lz-compressor}). The name of the program can't begin with @samp{-}. These options override the values set in @file{zutils.conf}. The compression program used must meet three requirements: @anchor{compressor-requirements} @enumerate @item When called with the option @option{-d} and without file names, it must read compressed data from the standard input and produce decompressed data on the standard output. @item If the option @option{-q} is passed to zutils, the compression program must also accept it. @item It must return 0 if no errors occurred, and a non-zero value otherwise. @end enumerate @end table @node Configuration @chapter The configuration file 'zutils.conf' @cindex zutils.conf @file{zutils.conf} is the runtime configuration file for zutils. In it you may define the compressor name and options to be used for each format. @file{zutils.conf} is optional; you don't need to install it in order to run zutils. The compressors specified in the command line override those specified in @file{zutils.conf}. You may copy the system @file{zutils.conf} file @file{$@{sysconfdir@}/zutils.conf} to @file{$XDG_CONFIG_HOME/zutils.conf} and customize these options as you like. (@env{XDG_CONFIG_HOME} defaults to @file{$HOME/.config}). The file syntax is fairly obvious (and there are further instructions in it): @enumerate @item Any line beginning with @samp{#} is a comment line. @item Each non-comment line defines the command to be used for the corresponding format, with the syntax: @example = [options] @end example where is one of @samp{bz2}, @samp{gz}, @samp{lz}, @samp{xz}, or @samp{zst}. @end enumerate @node Zcat @chapter Zcat @cindex zcat @command{zcat} copies each @var{file} argument to standard output in sequence. If any file given is compressed, its decompressed content is copied. If a file given does not exist, and its name does not end with one of the known extensions, @command{zcat} tries the compressed file names corresponding to the formats supported. If a file fails to decompress, @command{zcat} continues copying the rest of the files. If a file is specified as @samp{-}, data are read from standard input, decompressed if needed, and sent to standard output. Data read from standard input must be of the same type; all uncompressed or all in the same compressed format. If no files are specified, recursive searches examine the current working directory, and nonrecursive searches read standard input. The format for running @command{zcat} is: @example zcat [@var{options}] [@var{files}] @end example @noindent Exit status is 0 if no errors occurred, 1 otherwise. @command{zcat} supports the following options: @table @code @item -A @itemx --show-all Equivalent to @option{-vET}. @item -b @itemx --number-nonblank Number all nonblank output lines, starting with 1. The line count is unlimited. @item -e Equivalent to @option{-vE}. @item -E @itemx --show-ends Print a @samp{$} after the end of each line. @item -n @itemx --number Number all output lines, starting with 1. The line count is unlimited. @item -O @var{format} @itemx --force-format=@var{format} Force the compressed format given. Valid values for @var{format} are @samp{bz2}, @samp{gz}, @samp{lz}, @samp{xz}, @samp{zst}, and @samp{un} for @samp{uncompressed}. If this option is used, the files are passed to the corresponding decompressor (or transmitted unmodified) without verifying their format, and the exact file name must be given. Other names won't be tried. @item -q @itemx --quiet Quiet operation. Suppress all messages. @item -r @itemx --recursive For each directory operand, read and process all files in that directory, recursively. Follow symbolic links given in the command line, but skip symbolic links that are encountered recursively. @item -R @itemx --dereference-recursive For each directory operand, read and process all files in that directory, recursively, following all symbolic links. @item -s @itemx --squeeze-blank Replace multiple adjacent blank lines with a single blank line. @item -t Equivalent to @option{-vT}. @item -T @itemx --show-tabs Print TAB characters as @samp{^I}. @item -v @itemx --show-nonprinting Print control characters except for LF (newline) and TAB using @samp{^} notation and precede characters larger than 127 with @samp{M-} (which stands for "meta"). @item --verbose Verbose mode. Show error messages. Repeating it increases the verbosity level. @xref{version}. @end table @node Zcmp @chapter Zcmp @cindex zcmp @command{zcmp} compares two files and, if they differ, writes to standard output the first byte and line number where they differ. Bytes and lines are numbered starting with 1. A hyphen @samp{-} used as a @var{file} argument means standard input. If any file given is compressed, its decompressed content is used. Compressed files are decompressed on the fly; no temporary files are created. The format for running @command{zcmp} is: @example zcmp [@var{options}] @var{file1} [@var{file2}] @end example @noindent This compares @var{file1} to @var{file2}. The standard input is used only if @var{file1} or @var{file2} refers to standard input. If @var{file2} is omitted @command{zcmp} tries the following: @itemize - @item If @var{file1} is compressed, compares its decompressed contents with the corresponding uncompressed file (the name of @var{file1} with the extension removed). @item If @var{file1} is uncompressed, compares it with the decompressed contents of @var{file1}.[lz|bz2|gz|zst|xz] (the first one that is found). @end itemize @noindent An exit status of 0 means no differences were found, 1 means some differences were found, and 2 means trouble. @command{zcmp} supports the following options: @table @code @item -b @itemx --print-bytes Print the values of the differing bytes (in octal by default) followed by the bytes themselves in printable form. Print control bytes as a @samp{^} followed by a letter, and precede bytes larger than 127 with @samp{M-} (which stands for "meta"). @item -H @itemx --hexadecimal Print the values of the differing bytes in hexadecimal instead of octal. @item -i @var{size} @itemx --ignore-initial=@var{size} Ignore any differences in the first @var{size} bytes of the input files. Treat files with fewer than @var{size} bytes as if they were empty. If @var{size} is in the form @samp{@var{size1}:@var{size2}}, ignore the first @var{size1} bytes of the first input file and the first @var{size2} bytes of the second input file. @item -l @itemx --list Print the byte numbers (in decimal) and values (in octal by default) of all differing bytes. Bytes are numbered starting with 1. @item -n @var{count} @itemx --bytes=@var{count} Compare at most @var{count} input bytes. @item -O [@var{format1}][,@var{format2}] @itemx --force-format=[@var{format1}][,@var{format2}] Force the compressed formats given. Any of @var{format1} or @var{format2} may be omitted and the corresponding format will be automatically detected. Valid values for @var{format} are @samp{bz2}, @samp{gz}, @samp{lz}, @samp{xz}, @samp{zst}, and @samp{un} for @samp{uncompressed}. If at least one format is specified with this option, the file is passed to the corresponding decompressor (or transmitted unmodified) without verifying its format, and the exact file names of both @var{file1} and @var{file2} must be given. Other names won't be tried. @item -q @itemx --quiet @itemx --silent Suppress diagnostics written to standard error, even the @w{@samp{EOF on }} diagnostic. Byte differences are still written to standard output. (@option{-q} produces no output except byte differences). @item -s @itemx --script Write nothing to standard output or standard error when files differ, not even the @w{@samp{EOF on }} diagnostic; indicate differing files through exit status only. Diagnostic messages are still written to standard error when an error is encountered. (@option{-s} produces no output except error messages). @item -v @itemx --verbose Verbose mode. Undoes the effect of @option{--quiet}. Further -v's increase the verbosity level. @xref{version}. @end table Byte counts given as arguments to options may be expressed in decimal, hexadecimal, or octal (using the same syntax as integer constants in C++), and may be followed by a multiplier and an optional @samp{B} for "byte". Table of SI and binary prefixes (unit multipliers): @multitable {Prefix} {kilobyte (10^3 = 1000)} {|} {Prefix} {kibibyte (2^10 = 1024)} @item Prefix @tab Value @tab | @tab Prefix @tab Value @item k @tab kilobyte (10^3 = 1000) @tab | @tab Ki @tab kibibyte (2^10 = 1024) @item M @tab megabyte (10^6) @tab | @tab Mi @tab mebibyte (2^20) @item G @tab gigabyte (10^9) @tab | @tab Gi @tab gibibyte (2^30) @item T @tab terabyte (10^12) @tab | @tab Ti @tab tebibyte (2^40) @item P @tab petabyte (10^15) @tab | @tab Pi @tab pebibyte (2^50) @item E @tab exabyte (10^18) @tab | @tab Ei @tab exbibyte (2^60) @item Z @tab zettabyte (10^21) @tab | @tab Zi @tab zebibyte (2^70) @item Y @tab yottabyte (10^24) @tab | @tab Yi @tab yobibyte (2^80) @end multitable @node Zdiff @chapter Zdiff @cindex zdiff @command{zdiff} compares two files and, if they differ, writes to standard output the differences line by line. A hyphen @samp{-} used as a @var{file} argument means standard input. If any file given is compressed, its decompressed content is used. @command{zdiff} is a front end to the program diff and has the limitation that messages from diff refer to temporary file names instead of those specified. The format for running @command{zdiff} is: @example zdiff [@var{options}] @var{file1} [@var{file2}] @end example @noindent This compares @var{file1} to @var{file2}. The standard input is used only if @var{file1} or @var{file2} refers to standard input. If @var{file2} is omitted @command{zdiff} tries the following: @itemize - @item If @var{file1} is compressed, compares its decompressed contents with the corresponding uncompressed file (the name of @var{file1} with the extension removed). @item If @var{file1} is uncompressed, compares it with the decompressed contents of @var{file1}.[lz|bz2|gz|zst|xz] (the first one that is found). @end itemize @noindent An exit status of 0 means no differences were found, 1 means some differences were found, and 2 means trouble. @command{zdiff} supports the following options (some options only work if the diff program used supports them): @table @code @item -a @itemx --text Treat all files as text. @item -b @itemx --ignore-space-change Ignore changes in the amount of white space. @item -B @itemx --ignore-blank-lines Ignore changes whose lines are all blank. @item -c Use the context output format. @item -C @var{n} @itemx --context=@var{n} Same as -c but use @var{n} lines of context. @item -d @itemx --minimal Try hard to find a smaller set of changes. @item -E @itemx --ignore-tab-expansion Ignore changes due to tab expansion. @item -i @itemx --ignore-case Ignore case differences in file contents. @item -O [@var{format1}][,@var{format2}] @itemx --force-format=[@var{format1}][,@var{format2}] Force the compressed formats given. Any of @var{format1} or @var{format2} may be omitted and the corresponding format will be automatically detected. Valid values for @var{format} are @samp{bz2}, @samp{gz}, @samp{lz}, @samp{xz}, @samp{zst}, and @samp{un} for @samp{uncompressed}. If at least one format is specified with this option, the file is passed to the corresponding decompressor (or transmitted unmodified) without verifying its format, and the exact file names of both @var{file1} and @var{file2} must be given. Other names won't be tried. @item -p @itemx --show-c-function Show which C function each change is in. @item -q @itemx --brief Output only whether files differ. @item -s @itemx --report-identical-files Report when two files are identical. @item -t @itemx --expand-tabs Expand tabs to spaces in output. @item -T @itemx --initial-tab Make tabs line up by prepending a tab. @item -u Use the unified output format. @item -U @var{n} @itemx --unified=@var{n} Same as -u but use @var{n} lines of context. @item -v @itemx --verbose When specified before @option{--version}, print the version of the diff program used. Further -v's increase the verbosity level. @xref{version}. @item -w @itemx --ignore-all-space Ignore all white space. @item -W @var{columns} @itemx --width=@var{columns} Output at most the specified number of print columns per line in side by side format. @item -y @itemx --side-by-side Use the side by side output format. @end table @node Zgrep @chapter Zgrep @cindex zgrep @command{zgrep} is a front end to the program grep that allows transparent search on any combination of compressed and uncompressed files. If any file given is compressed, its decompressed content is used. If a file given does not exist, and its name does not end with one of the known extensions, @command{zgrep} tries the compressed file names corresponding to the formats supported. If a file fails to decompress, @command{zgrep} continues searching the rest of the files. If a file is specified as @samp{-}, data are read from standard input, decompressed if needed, and fed to grep. Data read from standard input must be of the same type; all uncompressed or all in the same compressed format. If no files are specified, recursive searches examine the current working directory, and nonrecursive searches read standard input. For efficiency reasons, @command{zgrep} does not always read all its input. For example, the shell command @w{@samp{base64 -d foo | zgrep -q X}} can cause @command{zgrep} to exit immediately after reading a line containing @samp{X}, without bothering to read the rest of its input data. This in turn can cause base64 to exit with a nonzero status because base64 cannot write to its output pipe after @command{zgrep} exits. The format for running @command{zgrep} is: @example zgrep [@var{options}] @var{pattern} [@var{files}] @end example @noindent An exit status of 0 means at least one match was found, 1 means no matches were found, and 2 means trouble. @command{zgrep} supports the following options (Some options only work if the grep program used supports them. Options -h, -H, -r, -R, and -Z are managed by @command{zgrep} and not passed to grep): @table @code @item -a @itemx --text Treat all files as text. @item -A @var{n} @itemx --after-context=@var{n} Print @var{n} lines of trailing context. @item -b @itemx --byte-offset Print the byte offset of each line. @item -B @var{n} @itemx --before-context=@var{n} Print @var{n} lines of leading context. @item -c @itemx --count Only print a count of matching lines per file. @item -C @var{n} @itemx --context=@var{n} Print @var{n} lines of output context. @item --color[=@var{when}] Show matched strings in color. @var{when} is @samp{never}, @samp{always}, or @samp{auto}. @item -e @var{pattern} @itemx --regexp=@var{pattern} Use @var{pattern} as the pattern to match. @item -E @itemx --extended-regexp Interpret @var{pattern} as an extended regular expression (ERE). @item -f @var{file} @itemx --file=@var{file} Obtain patterns from @var{file}, one per line.@* When searching in several files at once, command substitution can be used with @option{-e} to read @var{file} only once, for example if @var{file} is not a regular file: @w{@samp{zgrep -e "$(cat @var{file})" file1.lz file2.gz}} @item -F @itemx --fixed-strings Interpret @var{pattern} as a set of newline-separated strings. @item -G @itemx --basic-regexp Interpret @var{pattern} as a basic regular expression (BRE). This is the default. @item -h @itemx --no-filename Suppress the prefixing of file names on output when multiple files are searched. @item -H @itemx --with-filename Print the file name for each match. @item -i @itemx --ignore-case Ignore case distinctions. @item -I Ignore binary files. @item -l @itemx --files-with-matches Only print names of files containing at least one match. Stop reading each file on the first match. @item -L @itemx --files-without-match Only print names of files not containing any matches. Stop reading each file on the first match.@* Note: option -L fails (prints wrong results, returns wrong status, and even hangs) when using GNU grep versions 3.2 to 3.4 inclusive because of a wrong change in the exit status of grep, which was reverted in GNU grep 3.5. @item --label=@var{label} Display input actually coming from standard input as input coming from file @var{label}. @item --line-buffered Use line buffering on output. This may cause a performance penalty. @item -m @var{n} @itemx --max-count=@var{n} Stop after @var{n} matches. @item -n @itemx --line-number Prefix each matched line with its line number in the input file. @item -o @itemx --only-matching Show only the part of matching lines that actually matches @var{pattern}. @item -O @var{format} @itemx --force-format=@var{format} Force the compressed format given. Valid values for @var{format} are @samp{bz2}, @samp{gz}, @samp{lz}, @samp{xz}, @samp{zst}, and @samp{un} for @samp{uncompressed}. If this option is used, the files are passed to the corresponding decompressor (or transmitted unmodified) without verifying their format, and the exact file name must be given. Other names won't be tried. @item -P @itemx --perl-regexp Interpret @var{pattern} as a Perl-compatible regular expression (PCRE). @item -q @itemx --quiet @itemx --silent Suppress all messages. Exit immediately with zero status if any match is found, even if an error was detected. @item -r @itemx --recursive For each directory operand, read and process all files in that directory, recursively. Follow symbolic links given in the command line, but skip symbolic links that are encountered recursively. @item -R @itemx --dereference-recursive For each directory operand, read and process all files in that directory, recursively, following all symbolic links. @item -s @itemx --no-messages Suppress error messages about nonexistent or unreadable files. @item -T @itemx --initial-tab Make sure that the first character of actual line content lies on a tab stop, so that the alignment of tabs looks normal. @item -U @itemx --binary Use binary I/O on platforms affected by the bug known as "text mode I/O". (MS-DOS, MS-Windows, OS/2). @item -v @itemx --invert-match Select non-matching lines. @item --verbose Verbose mode. Show error messages. When specified before @option{--version}, print the version of the grep program used. Repeating it increases the verbosity level. @xref{version}. @item -w @itemx --word-regexp Match only whole words. @item -x @itemx --line-regexp Match only whole lines. @item -Z @itemx --null Output a zero byte (the ASCII NUL character) instead of the character that normally follows a file name. For example, @w{@samp{zgrep -lZ}} outputs a zero byte after each file name instead of the usual newline. This option makes the output unambiguous, even in the presence of file names containing unusual characters like newlines. @end table @node Ztest @chapter Ztest @cindex ztest @command{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 @samp{-}, 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, @command{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. Bzip2, gzip, and lzip are the primary formats. Xz and zstd are optional. If the decompressor for the xz or zstd formats is not found, the corresponding files are ignored. Note that error detection in the xz format is broken. First, some xz files lack integrity information. Second, not all xz decompressors can @uref{http://www.nongnu.org/lzip/xz_inadequate.html#fragmented,,verify the integrity} of all xz files. Third, section 2.1.1.2 'Stream Flags' of the @uref{http://tukaani.org/xz/xz-file-format.txt,,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. @c We can only hope that xz is soon abandoned. The format for running @command{ztest} is: @example ztest [@var{options}] [@var{files}] @end example @noindent 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. @command{ztest} supports the following options: @table @code @item -O @var{format} @itemx --force-format=@var{format} Force the compressed format given. Valid values for @var{format} are @samp{bz2}, @samp{gz}, @samp{lz}, @samp{xz}, and @samp{zst}. If this option is used, the files are passed to the corresponding decompressor without verifying their format, and any files in a format that the decompressor can't understand will fail. @item -q @itemx --quiet Quiet operation. Suppress all messages. @item -r @itemx --recursive For each directory operand, read and process all files in that directory, recursively. Follow symbolic links given in the command line, but skip symbolic links that are encountered recursively. @item -R @itemx --dereference-recursive For each directory operand, read and process all files in that directory, recursively, following all symbolic links. @item -v @itemx --verbose Verbose mode. Show the verify status for each file processed. Further -v's increase the verbosity level. @xref{version}. @end table @node Zupdate @chapter Zupdate @cindex zupdate @command{zupdate} recompresses files from bzip2, gzip, xz, and zstd formats to lzip format. Each original is compared with the new file and then deleted. Only regular files with standard file name extensions are recompressed, other files are ignored. Compressed files are decompressed and then recompressed on the fly; no temporary files are created. If an error happens while recompressing a file, @command{zupdate} exits immediately without recompressing the rest of the files. The lzip format is chosen as destination because it is the most appropriate for long-term data archiving. If no files are specified, recursive searches examine the current working directory, and nonrecursive searches do nothing. If the lzip compressed version of a file already exists, the file is skipped unless the option @option{--force} is given. In this case, if the comparison with the existing lzip version fails, an error is returned and the original file is not deleted. The operation of @command{zupdate} is meant to be safe and not cause any data loss. Therefore, existing lzip compressed files are never overwritten nor deleted. Combining the options @option{--force} and @option{--keep}, as in @w{@samp{zupdate -f -k *.gz}}, verifies that there are no differences between each pair of files in a multiformat set of files. The names of the original files must have one of the following extensions:@* @samp{.bz2}, @samp{.gz}, @samp{.xz}, @samp{.zst}, or @samp{.Z}, which are recompressed to @samp{.lz};@* @samp{.tbz}, @samp{.tbz2}, @samp{.tgz}, @samp{.txz}, or @samp{.tzst}, which are recompressed to @samp{.tlz}.@* Keeping the combined extensions @w{(@samp{.tgz} ---> @samp{.tlz})} may be useful when recompressing Slackware packages, for example. Bzip2, gzip, and lzip are the primary formats. Xz and zstd are optional. If the decompressor for the xz or zstd formats is not found, the corresponding files are ignored. Recompressing a file is much like copying or moving it. Therefore @command{zupdate} preserves the access and modification dates, permissions, and, if you have appropriate privileges, ownership of the file just as @w{@samp{cp -p}} does. (If the user ID or the group ID can't be duplicated, the file permission bits S_ISUID and S_ISGID are cleared). The format for running @command{zupdate} is: @example zupdate [@var{options}] [@var{files}] @end example @noindent Exit status is 0 if all the compressed files were successfully recompressed (if needed), compared, and deleted (if requested). 1 if a non-fatal error occurred (file not found or not regular, or has invalid format, or can't be deleted). 2 if a fatal error occurred (invalid command line options, compressor can't be run, or comparison fails). @command{zupdate} supports the following options: @table @code @item -d @var{dir} @itemx --destdir=@var{dir} Write recompressed files to another directory, using @var{dir} as base directory, instead of writing them in the same directory as the original files. In recursive mode, this is done by replacing each directory specified in the command line with @var{dir} to produce the recompressed file names. For example, @w{@samp{zupdate -r -d @var{dir} ../a}} recompresses a file named @file{../a/b/c.gz} to @file{@var{dir}/b/c.lz}. Regular files specified in the command line are recompressed directly into @var{dir}. For example, @w{@samp{zupdate -d @var{dir} ../a/b/c.gz}} writes the recompressed file to @file{@var{dir}/c.lz}. This option allows recompressing files from a read-only file system to another place without the need to copy or link them to the destination directory first. (Remember to use option @option{--keep} when recompressing read-only files to avoid warnings about files that can't be deleted). @item -e @itemx --expand-extensions Expand combined file name extensions; recompress @samp{.tbz}, @samp{.tbz2}, @samp{.tgz}, @samp{.txz}, and @samp{.tzst} to @samp{tar.lz}. @item -f @itemx --force Don't skip a file for which a lzip compressed version already exists. @option{--force} compares the content of the input file with the content of the existing lzip file and deletes the input file if both contents are identical. @item -i @itemx --ignore-errors Ignore non-fatal errors. (See exit status above). @item -k @itemx --keep Keep (don't delete) the input file after comparing it with the lzip file. Use it when recompressing files from a read-only file system. (See option @option{--destdir} above). @item -l @itemx --lzip-verbose Pass one option @option{-v} to the lzip compressor so that it shows the compression ratio for each file processed. Using lzip 1.15 or newer, a second @option{-l} shows the progress of compression. Use it together with @option{-v} to see the name of the file. @item -q @itemx --quiet Quiet operation. Suppress all messages. @item -r @itemx --recursive For each directory operand, read and process all files in that directory, recursively. Follow symbolic links given in the command line, but skip symbolic links that are encountered recursively. @item -R @itemx --dereference-recursive For each directory operand, read and process all files in that directory, recursively, following all symbolic links. @item -v @itemx --verbose Verbose mode. Show the files being processed. A second @option{-v} also shows the files being ignored and increases the verbosity level. @xref{version}. @item -0 .. -9 Set the compression level of lzip. By default @command{zupdate} passes @option{-9} to lzip. Custom compression options can be passed to lzip with the option @option{--lz}. For example @w{@option{--lz='lzip -9 -s64MiB'}}. @anchor{lz-compressor} @item --lz=@var{command} Set compression command. @var{command} may include arguments. For example @w{@option{--lz='plzip --threads=2'}}. The name of the program can't begin with @samp{-}. This option overrides the value set in @file{zutils.conf}. The compression program used does not need to implement decompression (@pxref{compressor-requirements}), but it must implement at least the compression level option @option{-9} and the option @w{@option{-o @var{file}}} to write the compressed output to @var{file}. @uref{http://www.nongnu.org/lzip/manual/tarlz_manual.html,,tarlz} meets these requirements, and therefore can be used to recompress POSIX tar archives by using a command like @w{@samp{zupdate --lz='tarlz -9 -z --no-solid' archive.tar.gz}}. @ifnothtml @xref{Top,tarlz manual,,tarlz}. @end ifnothtml @end table @node Problems @chapter Reporting bugs @cindex bugs @cindex getting help There are probably bugs in zutils. There are certainly errors and omissions in this manual. If you report them, they will get fixed. If you don't, no one will ever know about them and they will remain unfixed for all eternity, if not longer. If you find a bug in zutils, please send electronic mail to @email{zutils-bug@@nongnu.org}. Include the version number, which you can find by running @w{@samp{zupdate --version}}. @node Concept index @unnumbered Concept index @printindex cp @bye