path: root/doc/zutils.texi

\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
<format> = <compressor> [options]
@end example
where <format> 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