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Zutils Manual

This manual is for Zutils (version 1.2, 1 February 2014).


Copyright © 2009, 2010, 2011, 2012, 2013, 2014 Antonio Diaz Diaz.

This manual is free documentation: you have unlimited permission to copy, distribute and modify it.


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1 Introduction

Zutils is a collection of utilities able to deal with 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 '--recursive' option is very efficient in those utilities supporting it.

The provided utilities are zcat, zcmp, zdiff, zgrep, ztest and zupdate.
The supported formats are bzip2, gzip, lzip and xz.
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 with 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.

LANGUAGE NOTE: Uncompressed = not compressed = plain data; it may never have been compressed. Decompressed is used to refer to data which has undergone the process of decompression.


Numbers given as arguments to options (positions, sizes) may be followed by a multiplier and an optional 'B' for "byte".

Table of SI and binary prefixes (unit multipliers):

Prefix Value | Prefix Value
k kilobyte (10^3 = 1000) | Ki kibibyte (2^10 = 1024)
M megabyte (10^6) | Mi mebibyte (2^20)
G gigabyte (10^9) | Gi gibibyte (2^30)
T terabyte (10^12) | Ti tebibyte (2^40)
P petabyte (10^15) | Pi pebibyte (2^50)
E exabyte (10^18) | Ei exbibyte (2^60)
Z zettabyte (10^21) | Zi zebibyte (2^70)
Y yottabyte (10^24) | Yi yobibyte (2^80)


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2 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.

'-h'
'--help'
Print an informative help message describing the options and exit. Zgrep only supports the '--help' form of this option.
'-V'
'--version'
Print the version number on the standard output and exit.
'-N'
'--no-rcfile'
Don't read the runtime configuration file 'zutilsrc'.
'--bz2=command'
'--gz=command'
'--lz=command'
'--xz=command'
Set program (may include arguments) to be used as (de)compressor for the given format. These options override the values set in zutilsrc. The compression program used must meet three requirements:
  1. When called with the '-d' option, it must read compressed data from the standard input and produce decompressed data on the standard output.
  2. If the '-q' option is passed to zutils, the compression program must also accept it.
  3. It must return 0 if no errors occurred, and a non-zero value otherwise.


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3 The zutilsrc 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 zutilsrc file is optional; you do not need to install it in order to run zutils.

The compressors specified in the command line override those specified in the zutilsrc file.

You may copy the system zutilsrc file ${sysconfdir}/zutilsrc to $HOME/.zutilsrc and customize these options as you like. The file syntax is fairly obvious (and there are further instructions in it):

  1. Any line beginning with '#' is a comment line.
  2. Each non-comment line defines the command to be used for the given format, with the syntax:
              <format> = <compressor> [options]
    

    where <format> is one of 'bz2', 'gz', 'lz' or 'xz'.


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4 Zcat

Zcat copies each given file ('-' means standard input), 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 supported formats.

If no files are specified, data is 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.

The format for running zcat is:

     zcat [options] [files]

Exit status is 0 if no errors occurred, non-zero otherwise.

Zcat supports the following options:

'-A'
'--show-all'
Equivalent to '-vET'.
'-b'
'--number-nonblank'
Number all nonblank output lines, starting with 1. The line count is unlimited.
'-e'
Equivalent to '-vE'.
'-E'
'--show-ends'
Print a '$' after the end of each line.
'--format=fmt'
Force the given compression format. Valid values for fmt are 'bz2', 'gz', 'lz' and 'xz'. If this option is used, the exact file name must be given. Other names won't be tried.
'-n'
'--number'
Number all output lines, starting with 1. The line count is unlimited.
'-q'
'--quiet'
Quiet operation. Suppress all messages.
'-r'
'--recursive'
Operate recursively on directories.
'-s'
'--squeeze-blank'
Replace multiple adjacent blank lines with a single blank line.
'-t'
Equivalent to '-vT'.
'-T'
'--show-tabs'
Print TAB characters as '^I'.
'-v'
'--show-nonprinting'
Print control characters except for LF (newline) and TAB using '^' notation and precede characters larger than 127 with 'M-' (which stands for "meta").
'--verbose'
Verbose mode. Show error messages.


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5 Zcmp

Zcmp compares two files ('-' 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:

     zcmp [options] file1 [file2]

This compares file1 to file2. If file2 is omitted zcmp tries the following:

  1. If file1 is compressed, compares its decompressed contents with the corresponding uncompressed file (the name of file1 with the extension removed).
  2. If file1 is uncompressed, compares it with the decompressed contents of file1.[lz|bz2|gz|xz] (the first one that is found).
  3. If no suitable file is found, compares file1 with data read from standard input.

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:

'-b'
'--print-bytes'
Print the differing bytes. Print control bytes as a '^' followed by a letter, and precede bytes larger than 127 with 'M-' (which stands for "meta").
'--format=[fmt1][,fmt2]'
Force the given compression formats. Any of fmt1 or fmt2 may be omitted and the corresponding format will be automatically detected. Valid values for fmt are 'bz2', 'gz', 'lz' and 'xz'. If at least one format is specified with this option, the exact file names of both file1 and file2 must be given. Other names won't be tried.
'-i size'
'--ignore-initial=size'
Ignore any differences in the first size bytes of the input files. Treat files with fewer than size bytes as if they were empty. If size is in the form 'size1,size2', ignore the first size1 bytes of the first input file and the first size2 bytes of the second input file.
'-l'
'-v'
'--list'
'--verbose'
Print the byte numbers (in decimal) and values (in octal) of all differing bytes.
'-n count'
'--bytes=count'
Compare at most count input bytes.
'-q'
'-s'
'--quiet'
'--silent'
Do not print anything; only return an exit status indicating whether the files differ.


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6 Zdiff

Zdiff compares two files ('-' 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 filenames instead of those specified.

The format for running zdiff is:

     zdiff [options] file1 [file2]

This compares file1 to file2. If file2 is omitted zdiff tries the following:

  1. If file1 is compressed, compares its decompressed contents with the corresponding uncompressed file (the name of file1 with the extension removed).
  2. If file1 is uncompressed, compares it with the decompressed contents of file1.[lz|bz2|gz|xz] (the first one that is found).
  3. If no suitable file is found, compares file1 with data read from standard input.

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:

'-a'
'--text'
Treat all files as text.
'-b'
'--ignore-space-change'
Ignore changes in the amount of white space.
'-B'
'--ignore-blank-lines'
Ignore changes whose lines are all blank.
'-c'
Use the context output format.
'-C n'
'--context=n'
Same as -c but use n lines of context.
'-d'
'--minimal'
Try hard to find a smaller set of changes.
'-E'
'--ignore-tab-expansion'
Ignore changes due to tab expansion.
'--format=[fmt1][,fmt2]'
Force the given compression formats. Any of fmt1 or fmt2 may be omitted and the corresponding format will be automatically detected. Valid values for fmt are 'bz2', 'gz', 'lz' and 'xz'. If at least one format is specified with this option, the exact file names of both file1 and file2 must be given. Other names won't be tried.
'-i'
'--ignore-case'
Ignore case differences in file contents.
'-p'
'--show-c-function'
Show which C function each change is in.
'-q'
'--brief'
Output only whether files differ.
'-s'
'--report-identical-files'
Report when two files are identical.
'-t'
'--expand-tabs'
Expand tabs to spaces in output.
'-T'
'--initial-tab'
Make tabs line up by prepending a tab.
'-u'
Use the unified output format.
'-U n'
'--unified=n'
Same as -u but use n lines of context.
'-w'
'--ignore-all-space'
Ignore all white space.


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7 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 supported formats.

If no files are specified, data is 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.

The format for running zgrep is:

     zgrep [options] pattern [files]

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:

'-a'
'--text'
Treat all files as text.
'-A n'
'--after-context=n'
Print n lines of trailing context.
'-b'
'--byte-offset'
Print the byte offset of each line.
'-B n'
'--before-context=n'
Print n lines of leading context.
'-c'
'--count'
Only print a count of matching lines per file.
'-C n'
'--context=n'
Print n lines of output context.
'-e pattern'
'--regexp=pattern'
Use pattern as the pattern to match.
'-E'
'--extended-regexp'
Treat pattern as an extended regular expression.
'-f file'
'--file=file'
Obtain patterns from file, one per line.
'-F'
'--fixed-strings'
Treat pattern as a set of newline-separated strings.
'--format=fmt'
Force the given compression format. Valid values for fmt are 'bz2', 'gz', 'lz' and 'xz'. If this option is used, the exact file name must be given. Other names won't be tried.
'-h'
'--no-filename'
Suppress the prefixing of filenames on output when multiple files are searched.
'-H'
'--with-filename'
Print the filename for each match.
'-i'
'--ignore-case'
Ignore case distinctions.
'-I'
Ignore binary files.
'-l'
'--files-with-matches'
Only print names of files containing at least one match.
'-L'
'--files-without-match'
Only print names of files not containing any matches.
'-m n'
'--max-count=n'
Stop after n matches.
'-n'
'--line-number'
Prefix each matched line with its line number in the input file.
'-o'
'--only-matching'
Show only the part of matching lines that actually matches pattern.
'-q'
'--quiet'
Suppress all messages. Exit immediately with zero status if any match is found, even if an error was detected.
'-r'
'--recursive'
Operate recursively on directories.
'-s'
'--no-messages'
Suppress error messages about nonexistent or unreadable files.
'-v'
'--invert-match'
Select non-matching lines.
'--verbose'
Verbose mode. Show error messages.
'-w'
'--word-regexp'
Match only whole words.
'-x'
'--line-regexp'
Match only whole lines.


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8 Ztest

Ztest verifies the integrity of the specified compressed files. Uncompressed files are ignored. If no files are specified, the integrity of compressed data read from standard input is verified. Data read from standard input must be all in the same compression format.

Note that some xz files lack integrity information, and therefore can't be verified as reliably as the other formats can.

The format for running ztest is:

     ztest [options] [files]

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:

'--format=fmt'
Force the given compression format. Valid values for fmt are 'bz2', 'gz', 'lz' and 'xz'. If this option is used, all files not in the given format will fail.
'-q'
'--quiet'
Quiet operation. Suppress all messages.
'-r'
'--recursive'
Operate recursively on directories.
'-v'
'--verbose'
Verbose mode. Show the verify status for each file processed.
Further -v's increase the verbosity level.


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9 Zupdate

Zupdate recompresses files from bzip2, gzip, and xz formats to lzip format. The originals are compared with the new files 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. The lzip format is chosen as destination because it is by far the most appropriate for long-term data archiving.

If the lzip compressed version of a file already exists, the file is skipped unless the '--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.

The names of the original files must have one of the following extensions: '.bz2', '.tbz', '.tbz2', '.gz', '.tgz', '.xz', '.txz'. The files produced have the extensions '.lz' or '.tar.lz'.

The format for running zupdate is:

     zupdate [options] [files]

Exit status is 0 if all the compressed files were successfully recompressed (if needed), compared and deleted. Non-zero otherwise.

Zupdate supports the following options:

'-f'
'--force'
Do not skip a file for which a lzip compressed version already exists. '--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.
'-k'
'--keep'
Keep (don't delete) the input file after comparing it with the lzip file.
'-l'
'--lzip-verbose'
Pass a '-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 '-l' shows the progress of compression. Use it together with '-v' to see the name of the file.
'-q'
'--quiet'
Quiet operation. Suppress all messages.
'-r'
'--recursive'
Operate recursively on directories.
'-v'
'--verbose'
Verbose mode. Show the files being processed. A second '-v' also shows the files being ignored.
'-0 .. -9'
Set the compression level of lzip. By default zupdate passes '-9' to lzip.


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10 Reporting bugs

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 zutils-bug@nongnu.org. Include the version number, which you can find by running 'zupdate --version'.


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