path: root/doc/zutils.info

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INFO-DIR-SECTION Data Compression
START-INFO-DIR-ENTRY
* Zutils: (zutils).             Utilities dealing with compressed files
END-INFO-DIR-ENTRY


File: zutils.info,  Node: Top,  Next: Introduction,  Up: (dir)

Zutils Manual
*************

This manual is for Zutils (version 1.7, 13 February 2018).

* 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


   Copyright (C) 2009-2018 Antonio Diaz Diaz.

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


File: zutils.info,  Node: Introduction,  Next: Common options,  Prev: Top,  Up: Top

1 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 '--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.
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.  *Note compressor-requirements::.

   FORMAT NOTE 1: The '--format' option allows the processing of a
subset of formats in recursive mode and when trying compressed file
names: 'zgrep foo -r --format=bz2,lz somedir somefile.tar'.

   FORMAT NOTE 2: If the '--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: '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.


   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)


File: zutils.info,  Node: Common options,  Next: The zutilsrc file,  Prev: Introduction,  Up: Top

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.

'-M FORMAT_LIST'
'--format=FORMAT_LIST'
     Process only the formats listed in the comma-separated
     FORMAT_LIST. Valid formats are 'bz2', 'gz', 'lz', 'xz' and 'un'
     for '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 FORMAT_LIST enables file names with the following
     extensions:

     bz2   enables   .bz2 .tbz .tbz2
     gz    enables   .gz .tgz
     lz    enables   .lz .tlz
     xz    enables   .xz .txz
     un    enables   any other file name

'-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. The name of the program can't begin with
     '-'. 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.



File: zutils.info,  Node: The zutilsrc file,  Next: Zcat,  Prev: Common options,  Up: Top

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 don't 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'.


File: zutils.info,  Node: Zcat,  Next: Zcmp,  Prev: The zutilsrc file,  Up: Top

4 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 supported formats.

   If no files are specified, or if a file is specified as '-', 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.

   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.

'-n'
'--number'
     Number all output lines, starting with 1. The line count is
     unlimited.

'-O FORMAT'
'--force-format=FORMAT'
     Force the given compression format. Valid values for FORMAT are
     'bz2', 'gz', 'lz' and '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.

'-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.



File: zutils.info,  Node: Zcmp,  Next: Zdiff,  Prev: Zcat,  Up: Top

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").

'-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.

'-O [FORMAT1][,FORMAT2]'
'--force-format=[FORMAT1][,FORMAT2]'
     Force the given compression formats. Any of FORMAT1 or FORMAT2 may
     be omitted and the corresponding format will be automatically
     detected. Valid values for FORMAT are 'bz2', 'gz', 'lz' and '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 FILE1 and FILE2 must be
     given. Other names won't be tried.

'-q'
'-s'
'--quiet'
'--silent'
     Don't print anything; only return an exit status indicating
     whether the files differ.



File: zutils.info,  Node: Zdiff,  Next: Zgrep,  Prev: Zcmp,  Up: Top

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 file names 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 (some options only work if the
diff program used supports them):

'-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.

'-i'
'--ignore-case'
     Ignore case differences in file contents.

'-O [FORMAT1][,FORMAT2]'
'--force-format=[FORMAT1][,FORMAT2]'
     Force the given compression formats. Any of FORMAT1 or FORMAT2 may
     be omitted and the corresponding format will be automatically
     detected. Valid values for FORMAT are 'bz2', 'gz', 'lz' and '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 FILE1 and FILE2 must be
     given. Other names won't be tried.

'-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.



File: zutils.info,  Node: Zgrep,  Next: Ztest,  Prev: Zdiff,  Up: Top

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, or if a file is specified as '-', 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.

   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 (some options only work if the
grep program used supports them):

'-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.

'--color[=WHEN]'
     Show matched strings in color. WHEN is 'never', 'always' or 'auto'.

'-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.
     When searching in several files at once, command substitution can
     be used with '-e' to read FILE only once, for example if FILE is
     not a regular file: 'zgrep -e "$(cat FILE)" file1.lz file2.gz'

'-F'
'--fixed-strings'
     Treat PATTERN as a set of newline-separated strings.

'-h'
'--no-filename'
     Suppress the prefixing of file names on output when multiple files
     are searched.

'-H'
'--with-filename'
     Print the file name 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.

'-O FORMAT'
'--force-format=FORMAT'
     Force the given compression format. Valid values for FORMAT are
     'bz2', 'gz', 'lz' and '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.

'-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.



File: zutils.info,  Node: Ztest,  Next: Zupdate,  Prev: Zgrep,  Up: Top

8 Ztest
*******

ztest verifies the integrity of the specified compressed files.
Uncompressed files are ignored. If no files are specified, or 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 compression format.

   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 2.1.1.2 '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.

   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:

'-O FORMAT'
'--force-format=FORMAT'
     Force the given compression format. Valid values for FORMAT are
     'bz2', 'gz', 'lz' and '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, '--force-format=gz' can test
     gzipped (.gz) and compress'd (.Z) files if the compressor used is
     GNU gzip.

'-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.



File: zutils.info,  Node: Zupdate,  Next: Problems,  Prev: Ztest,  Up: Top

9 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. 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.

   Combining the '--force' and '--keep' options, as in
'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: '.bz2', '.tbz', '.tbz2', '.gz', '.tgz', '.xz', '.txz'. The
files produced have the extensions '.lz' or '.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 "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:

     zupdate [OPTIONS] [FILES]

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:

'-f'
'--force'
     Don't 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.



File: zutils.info,  Node: Problems,  Next: Concept index,  Prev: Zupdate,  Up: Top

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'.


File: zutils.info,  Node: Concept index,  Prev: Problems,  Up: Top

Concept index
*************

[index]
* Menu:

* bugs:                                  Problems.              (line 6)
* common options:                        Common options.        (line 6)
* getting help:                          Problems.              (line 6)
* introduction:                          Introduction.          (line 6)
* the zutilsrc file:                     The zutilsrc file.     (line 6)
* zcat:                                  Zcat.                  (line 6)
* zcmp:                                  Zcmp.                  (line 6)
* zdiff:                                 Zdiff.                 (line 6)
* zgrep:                                 Zgrep.                 (line 6)
* ztest:                                 Ztest.                 (line 6)
* zupdate:                               Zupdate.               (line 6)



Tag Table:
Node: Top222
Node: Introduction1151
Node: Common options3775
Ref: compressor-requirements5533
Node: The zutilsrc file5905
Node: Zcat6830
Node: Zcmp8884
Node: Zdiff11343
Node: Zgrep14047
Node: Ztest17541
Node: Zupdate19375
Node: Problems22247
Node: Concept index22781

End Tag Table


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