\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 1 January 2019 @set VERSION 1.8 @dircategory Data 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 @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 * The zutilsrc file:: The zutils configuration file * 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{} 2009-2019 Antonio Diaz Diaz. This manual is free documentation: you have unlimited permission to copy, distribute and modify it. @node Introduction @chapter Introduction @cindex introduction 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 @samp{--recursive} option is very efficient in those utilities supporting it. @noindent 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. @xref{compressor-requirements}. FORMAT NOTE 1: The @samp{--format} option allows the processing of a subset of formats in recursive mode and when trying compressed file names: @w{@samp{zgrep foo -r --format=bz2,lz somedir somefile.tar}}. FORMAT NOTE 2: If the @samp{--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: @w{@samp{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. @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 options are available in all the utilities. Rather than writing identical descriptions for each of the programs, they are described here. @table @code @item -h @itemx --help Print an informative help message describing the options and exit. zgrep only supports the @samp{--help} form of this option. @item -V @itemx --version Print the version number on the standard output and exit. This version number should be included in all bug reports. @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} 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 @item lz @tab enables @tab .lz .tlz @item xz @tab enables @tab .xz .txz @item un @tab enables @tab any other file name @end multitable @item -N @itemx --no-rcfile Don't read the runtime configuration file @samp{zutilsrc}. @item --bz2=@var{command} @itemx --gz=@var{command} @itemx --lz=@var{command} @itemx --xz=@var{command} Set program (may include arguments) to be used as (de)compressor for the given format. The name of the program can't begin with @samp{-}. These options override the values set in @file{zutilsrc}. The compression program used must meet three requirements: @anchor{compressor-requirements} @enumerate @item When called with the @samp{-d} option, it must read compressed data from the standard input and produce decompressed data on the standard output. @item If the @samp{-q} option 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 The zutilsrc file @chapter The zutilsrc file @cindex the zutilsrc file @file{zutilsrc} is the runtime configuration file for zutils. In it you may define the compressor name and options to be used for each format. The @file{zutilsrc} file 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 the @file{zutilsrc} file. You may copy the system @file{zutilsrc} file @file{$@{sysconfdir@}/zutilsrc} to @file{$HOME/.zutilsrc} and customize these options as you like. 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 given format, with the syntax: @example = [options] @end example where is one of @samp{bz2}, @samp{gz}, @samp{lz} or @samp{xz}. @end enumerate @node Zcat @chapter Zcat @cindex zcat zcat copies each given file to standard output. If any given file is compressed, its decompressed content is used. If a given file does not exist, and its name does not end with one of the known extensions, zcat tries the compressed file names corresponding to the formats supported. If a file fails to decompress, 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 compression format. If no files are specified, recursive searches examine the current working directory, and nonrecursive searches read standard input. The format for running zcat is: @example zcat [@var{options}] [@var{files}] @end example @noindent Exit status is 0 if no errors occurred, non-zero otherwise. zcat supports the following options: @table @code @item -A @itemx --show-all Equivalent to @samp{-vET}. @item -b @itemx --number-nonblank Number all nonblank output lines, starting with 1. The line count is unlimited. @item -e Equivalent to @samp{-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 given compression format. Valid values for @var{format} are @samp{bz2}, @samp{gz}, @samp{lz} and @samp{xz}. If this option is used, the files are passed to the corresponding decompressor 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 in the command line, but skip symlinks 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 @samp{-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. @end table @node Zcmp @chapter Zcmp @cindex zcmp zcmp compares two files (@samp{-} means standard input), and if they differ, tells the first byte and line number where they differ. Bytes and lines are numbered starting with 1. If any given file is compressed, its decompressed content is used. Compressed files are decompressed on the fly; no temporary files are created. The format for running zcmp is: @example zcmp [@var{options}] @var{file1} [@var{file2}] @end example @noindent This compares @var{file1} to @var{file2}. If @var{file2} is omitted zcmp tries the following: @enumerate @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|xz] (the first one that is found). @item If no suitable file is found, compares @var{file1} with data read from standard input. @end enumerate @noindent An exit status of 0 means no differences were found, 1 means some differences were found, and 2 means trouble. zcmp supports the following options: @table @code @item -b @itemx --print-bytes Print the differing bytes. Print control bytes as a @samp{^} followed by a letter, and precede bytes larger than 127 with @samp{M-} (which stands for "meta"). @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 -v @itemx --list @itemx --verbose Print the byte numbers (in decimal) and values (in octal) of all differing bytes. @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 given compression formats. 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} and @samp{xz}. If at least one format is specified with this option, the file is passed to the corresponding decompressor 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 -s @itemx --quiet @itemx --silent Don't print anything; only return an exit status indicating whether the files differ. @end table @node Zdiff @chapter Zdiff @cindex zdiff zdiff compares two files (@samp{-} means standard input), and if they differ, shows the differences line by line. If any given file is compressed, its decompressed content is used. zdiff is a front end to the diff program and has the limitation that messages from diff refer to temporary file names instead of those specified. The format for running zdiff is: @example zdiff [@var{options}] @var{file1} [@var{file2}] @end example @noindent This compares @var{file1} to @var{file2}. If @var{file2} is omitted zdiff tries the following: @enumerate @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|xz] (the first one that is found). @item If no suitable file is found, compares @var{file1} with data read from standard input. @end enumerate @noindent An exit status of 0 means no differences were found, 1 means some differences were found, and 2 means trouble. 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. @itemx -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 given compression formats. 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} and @samp{xz}. If at least one format is specified with this option, the file is passed to the corresponding decompressor 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 -w @itemx --ignore-all-space Ignore all white space. @end table @node Zgrep @chapter Zgrep @cindex zgrep zgrep is a front end to the grep program that allows transparent search on any combination of compressed and uncompressed files. If any given file is compressed, its decompressed content is used. If a given file does not exist, and its name does not end with one of the known extensions, zgrep tries the compressed file names corresponding to the formats supported. If a file fails to decompress, 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 compression format. If no files are specified, recursive searches examine the current working directory, and nonrecursive searches read standard input. The format for running 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. zgrep supports the following options (some options only work if the grep program used supports them): @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 Treat @var{pattern} as an extended regular expression. @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 @code{-e} to read @var{file} only once, for example if @var{file} is not a regular file: @w{@code{zgrep -e "$(cat @var{file})" file1.lz file2.gz}} @item -F @itemx --fixed-strings Treat @var{pattern} as a set of newline-separated strings. @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. @item -L @itemx --files-without-match Only print names of files not containing any matches. @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 given compression format. Valid values for @var{format} are @samp{bz2}, @samp{gz}, @samp{lz} and @samp{xz}. If this option is used, the files are passed to the corresponding decompressor without verifying their format, and the exact file name must be given. Other names won't be tried. @item -q @itemx --quiet 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 in the command line, but skip symlinks 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 -v @itemx --invert-match Select non-matching lines. @item --verbose Verbose mode. Show error messages. @item -w @itemx --word-regexp Match only whole words. @item -x @itemx --line-regexp Match only whole lines. @end table @node Ztest @chapter Ztest @cindex ztest ztest verifies the integrity of the specified compressed files. Uncompressed files are 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 compression format. If a file fails to decompress, ztest continues verifying the rest of the files. If no files are specified, recursive searches examine the current working directory, and nonrecursive searches read standard input. 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 ztest is: @example ztest [@var{options}] [@var{files}] @end example @noindent The exit status is 0 if all compressed files verify OK, 1 if environmental problems (file not found, invalid flags, I/O errors, etc), 2 if any compressed file is corrupt or invalid. ztest supports the following options: @table @code @item -O @var{format} @itemx --force-format=@var{format} Force the given compression format. Valid values for @var{format} are @samp{bz2}, @samp{gz}, @samp{lz} and @samp{xz}. 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. For example, @samp{--force-format=gz} can test gzipped (.gz) and compress'd (.Z) files if the compressor used is GNU gzip. @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 in the command line, but skip symlinks 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. @end table @node Zupdate @chapter Zupdate @cindex zupdate zupdate recompresses files from bzip2, gzip, and xz 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, 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 @samp{--force} option 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 zupdate is meant to be safe and not produce any data loss. Therefore, existing lzip compressed files are never overwritten nor deleted. Combining the @samp{--force} and @samp{--keep} options, as in @w{@code{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{.tbz}, @samp{.tbz2}, @samp{.gz}, @samp{.tgz}, @samp{.xz}, @samp{.txz}. The files produced have the extensions @samp{.lz} or @samp{.tar.lz}. Recompressing a file is much like copying or moving it; therefore zupdate preserves the access and modification dates, permissions, and, when possible, ownership of the file just as @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 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). Non-zero otherwise. zupdate supports the following options: @table @code @item -f @itemx --force Don't skip a file for which a lzip compressed version already exists. @samp{--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 -k @itemx --keep Keep (don't delete) the input file after comparing it with the lzip file. @item -l @itemx --lzip-verbose Pass a @samp{-v} option to the lzip compressor so that it shows the compression ratio for each file processed. Using lzip 1.15 and newer, a second @samp{-l} shows the progress of compression. Use it together with @samp{-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 in the command line, but skip symlinks 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 @samp{-v} also shows the files being ignored. @item -0 .. -9 Set the compression level of lzip. By default zupdate passes @samp{-9} to lzip. @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{@code{zupdate --version}}. @node Concept index @unnumbered Concept index @printindex cp @bye