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doc/zutils.texi
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@ -6,8 +6,8 @@
@finalout
@c %**end of header
@set UPDATED 12 April 2022
@set VERSION 1.12-pre2
@set UPDATED 5 December 2022
@set VERSION 1.12-rc1
@dircategory Compression
@direntry
@ -38,7 +38,7 @@ 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
* Configuration:: The configuration file zutils.conf
* Zcat:: Concatenating compressed files
* Zcmp:: Comparing compressed files byte by byte
* Zdiff:: Comparing compressed files line by line
@ -66,21 +66,25 @@ is a collection of utilities able to process any combination of
compressed and uncompressed files transparently. If any file given,
including standard input, is compressed, its decompressed content is used.
Compressed files are decompressed on the fly; no temporary files are
created.
created. Data format is detected by its magic bytes, not by the file name
extension.
These utilities are not wrapper scripts but safer and more efficient C++
programs. In particular the option @samp{--recursive} is very efficient in
programs. In particular the option @option{--recursive} 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, xz, and zstd.@*
The utilities provided are @command{zcat}, @command{zcmp}, @command{zdiff},
@command{zgrep}, @command{ztest}, and @command{zupdate}.@*
The formats supported are bzip2, gzip,
@uref{http://www.nongnu.org/lzip/lzip.html,,lzip}, xz, and zstd.@*
Zutils uses external compressors. The compressor to be used for each format
is configurable at runtime.
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.
@command{zcat}, @command{zcmp}, @command{zdiff}, and @command{zgrep} are
improved replacements for the shell scripts provided by GNU gzip.
@command{ztest} is unique to zutils. @command{zupdate} is similar to gzip's
znew.
NOTE: Bzip2 and lzip provide well-defined values of exit status, which makes
them safe to use with zutils. Gzip and xz may return ambiguous warning
@ -88,7 +92,7 @@ values, making them less reliable back ends for zutils. Zstd currently does
not even document its exit status in its man page.
@xref{compressor-requirements}.
FORMAT NOTE 1: The option @samp{--format} allows the processing of a subset
FORMAT NOTE 1: The option @option{--format} allows the processing of a subset
of formats in recursive mode and when trying compressed file names. For
example, use the following command to search for the string @samp{foo} in
gzip and lzip files only:
@ -136,15 +140,19 @@ 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.
Print an informative help message describing the options and exit.
@command{zgrep} only supports the @option{--help} form of this option.
@anchor{version}
@item -V
@itemx --version
Print the version number on the standard output and exit.
This version number should be included in all bug reports.
In verbose mode, zdiff and zgrep print also the version of the diff or grep
program used respectively.
In verbose mode, @command{zdiff} and @command{zgrep} print also the version
of the diff or grep program used respectively. At verbosity level 1 (2 for
@command{zdiff} and @command{zgrep}) or higher, print also the versions of
the compressors used (perhaps limited by option @option{--format}). (The
compressors used must support the option @option{-V} for this to work).
@item -M @var{format_list}
@itemx --format=@var{format_list}
@ -171,29 +179,29 @@ extensions:
@item -N
@itemx --no-rcfile
Don't read the runtime configuration file @samp{zutilsrc}.
Don't read the runtime configuration file @file{zutils.conf}.
@item --bz2=@var{command}
@itemx --gz=@var{command}
@itemx --lz=@var{command}
@itemx --xz=@var{command}
@itemx --zst=@var{command}
Set program to be used as (de)compressor for the corresponding format.
Set program to be used as decompressor for the corresponding format.
@var{command} may include arguments. For example
@w{@samp{--lz='plzip --threads=2'}}. The program set with @samp{--lz} is
used for both compression and decompression. The others are used only for
decompression. 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:
@w{@option{--lz='plzip --threads=2'}}. @command{zupdate} uses @option{--lz}
for compression, not for decompression (@pxref{lz-compressor}). The name of
the program can't begin with @samp{-}. These options override the values set
in @file{zutils.conf}. The compression program used must meet three
requirements:
@anchor{compressor-requirements}
@enumerate
@item
When called with the option @samp{-d} and without file names, it must read
When called with the option @option{-d} and without file names, it must read
compressed data from the standard input and produce decompressed data on the
standard output.
@item
If the option @samp{-q} is passed to zutils, the compression program must
If the option @option{-q} is passed to zutils, the compression program must
also accept it.
@item
It must return 0 if no errors occurred, and a non-zero value otherwise.
@ -202,21 +210,22 @@ It must return 0 if no errors occurred, and a non-zero value otherwise.
@end table
@node The zutilsrc file
@chapter The zutils configuration file 'zutilsrc'
@cindex zutilsrc
@node Configuration
@chapter The configuration file 'zutils.conf'
@cindex zutils.conf
@file{zutilsrc} is the runtime configuration file for zutils. In it you
@file{zutils.conf} is the runtime configuration file for zutils. In it you
may define the compressor name and options to be used for each format.
@file{zutilsrc} is optional; you don't need to install it in order to run
@file{zutils.conf} is optional; you don't need to install it in order to run
zutils.
The compressors specified in the command line override those specified
in @file{zutilsrc}.
in @file{zutils.conf}.
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):
You may copy the system @file{zutils.conf} file @file{$@{sysconfdir@}/zutils.conf}
to @file{$XDG_CONFIG_HOME/zutils.conf} and customize these options as you like.
(@env{XDG_CONFIG_HOME} defaults to @file{$HOME/.config}). The file syntax is
fairly obvious (and there are further instructions in it):
@enumerate
@item
@ -236,12 +245,12 @@ where <format> is one of @samp{bz2}, @samp{gz}, @samp{lz}, @samp{xz}, or
@chapter Zcat
@cindex zcat
zcat copies each @var{file} argument to standard output in sequence. If any
file given is compressed, its decompressed content is copied. If a file
given does not exist, and its name does not end with one of the known
extensions, 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.
@command{zcat} copies each @var{file} argument to standard output in
sequence. If any file given is compressed, its decompressed content is
copied. If a file given does not exist, and its name does not end with one
of the known extensions, @command{zcat} tries the compressed file names
corresponding to the formats supported. If a file fails to decompress,
@command{zcat} continues copying the rest of the files.
If a file is specified as @samp{-}, data are read from standard input,
decompressed if needed, and sent to standard output. Data read from
@ -251,7 +260,7 @@ same compressed format.
If no files are specified, recursive searches examine the current working
directory, and nonrecursive searches read standard input.
The format for running zcat is:
The format for running @command{zcat} is:
@example
zcat [@var{options}] [@var{files}]
@ -260,12 +269,12 @@ zcat [@var{options}] [@var{files}]
@noindent
Exit status is 0 if no errors occurred, 1 otherwise.
zcat supports the following options:
@command{zcat} supports the following options:
@table @code
@item -A
@itemx --show-all
Equivalent to @samp{-vET}.
Equivalent to @option{-vET}.
@item -b
@itemx --number-nonblank
@ -273,7 +282,7 @@ Number all nonblank output lines, starting with 1. The line count is
unlimited.
@item -e
Equivalent to @samp{-vE}.
Equivalent to @option{-vE}.
@item -E
@itemx --show-ends
@ -286,10 +295,11 @@ Number all output lines, starting with 1. The line count is unlimited.
@item -O @var{format}
@itemx --force-format=@var{format}
Force the compressed format given. Valid values for @var{format} are
@samp{bz2}, @samp{gz}, @samp{lz}, @samp{xz}, and @samp{zst}. 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.
@samp{bz2}, @samp{gz}, @samp{lz}, @samp{xz}, @samp{zst}, and @samp{un} for
@samp{uncompressed}. If this option is used, the files are passed to the
corresponding decompressor (or transmitted unmodified) without verifying
their format, and the exact file name must be given. Other names won't be
tried.
@item -q
@itemx --quiet
@ -311,7 +321,7 @@ recursively, following all symbolic links.
Replace multiple adjacent blank lines with a single blank line.
@item -t
Equivalent to @samp{-vT}.
Equivalent to @option{-vT}.
@item -T
@itemx --show-tabs
@ -324,7 +334,8 @@ notation and precede characters larger than 127 with @samp{M-} (which
stands for "meta").
@item --verbose
Verbose mode. Show error messages.
Verbose mode. Show error messages. Repeating it increases the verbosity
level. @xref{version}.
@end table
@ -333,14 +344,14 @@ Verbose mode. Show error messages.
@chapter Zcmp
@cindex zcmp
zcmp compares two files and, if they differ, writes to standard output the
first byte and line number where they differ. Bytes and lines are numbered
starting with 1. A hyphen @samp{-} used as a @var{file} argument means
standard input. If any file given is compressed, its decompressed content is
used. Compressed files are decompressed on the fly; no temporary files are
created.
@command{zcmp} compares two files and, if they differ, writes to standard
output the first byte and line number where they differ. Bytes and lines are
numbered starting with 1. A hyphen @samp{-} used as a @var{file} argument
means standard input. If any file given is compressed, its decompressed
content is used. Compressed files are decompressed on the fly; no temporary
files are created.
The format for running zcmp is:
The format for running @command{zcmp} is:
@example
zcmp [@var{options}] @var{file1} [@var{file2}]
@ -349,7 +360,7 @@ zcmp [@var{options}] @var{file1} [@var{file2}]
@noindent
This compares @var{file1} to @var{file2}. The standard input is used only if
@var{file1} or @var{file2} refers to standard input. If @var{file2} is
omitted zcmp tries the following:
omitted @command{zcmp} tries the following:
@itemize -
@item
@ -365,14 +376,19 @@ contents of @var{file1}.[lz|bz2|gz|zst|xz] (the first one that is found).
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:
@command{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").
Print the values of the differing bytes (in octal by default) followed by
the bytes themselves in printable form. Print control bytes as a @samp{^}
followed by a letter, and precede bytes larger than 127 with @samp{M-}
(which stands for "meta").
@item -H
@itemx --hexadecimal
Print the values of the differing bytes in hexadecimal instead of octal.
@item -i @var{size}
@itemx --ignore-initial=@var{size}
@ -383,11 +399,9 @@ 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.
Print the byte numbers (in decimal) and values (in octal by default) of all
differing bytes. Bytes are numbered starting with 1.
@item -n @var{count}
@itemx --bytes=@var{count}
@ -398,33 +412,66 @@ Compare at most @var{count} input bytes.
Force the compressed formats given. Any of @var{format1} or @var{format2}
may be omitted and the corresponding format will be automatically detected.
Valid values for @var{format} are @samp{bz2}, @samp{gz}, @samp{lz},
@samp{xz}, and @samp{zst}. 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.
@samp{xz}, @samp{zst}, and @samp{un} for @samp{uncompressed}. If at least
one format is specified with this option, the file is passed to the
corresponding decompressor (or transmitted unmodified) without verifying its
format, and the exact file names of both @var{file1} and @var{file2} must be
given. Other names won't be tried.
@item -q
@itemx -s
@itemx --quiet
@itemx --silent
Don't print anything; only return an exit status indicating whether the
files differ.
Suppress diagnostics written to standard error, even the
@w{@samp{EOF on <name_of_shorter_file>}} diagnostic. Byte differences are
still written to standard output. (@option{-q} produces no output except
byte differences).
@item -s
@itemx --script
Write nothing to standard output or standard error when files differ, not
even the @w{@samp{EOF on <name_of_shorter_file>}} diagnostic; indicate
differing files through exit status only. Diagnostic messages are still
written to standard error when an error is encountered. (@option{-s}
produces no output except error messages).
@item -v
@itemx --verbose
Verbose mode. Undoes the effect of @option{--quiet}. Further -v's increase
the verbosity level. @xref{version}.
@end table
Byte counts given as arguments to options may be expressed in decimal,
hexadecimal, or octal (using the same syntax as integer constants in C++),
and may be followed by a multiplier and an optional @samp{B} for "byte".
Table of SI and binary prefixes (unit multipliers):
@multitable {Prefix} {kilobyte (10^3 = 1000)} {|} {Prefix} {kibibyte (2^10 = 1024)}
@item Prefix @tab Value @tab | @tab Prefix @tab Value
@item k @tab kilobyte (10^3 = 1000) @tab | @tab Ki @tab kibibyte (2^10 = 1024)
@item M @tab megabyte (10^6) @tab | @tab Mi @tab mebibyte (2^20)
@item G @tab gigabyte (10^9) @tab | @tab Gi @tab gibibyte (2^30)
@item T @tab terabyte (10^12) @tab | @tab Ti @tab tebibyte (2^40)
@item P @tab petabyte (10^15) @tab | @tab Pi @tab pebibyte (2^50)
@item E @tab exabyte (10^18) @tab | @tab Ei @tab exbibyte (2^60)
@item Z @tab zettabyte (10^21) @tab | @tab Zi @tab zebibyte (2^70)
@item Y @tab yottabyte (10^24) @tab | @tab Yi @tab yobibyte (2^80)
@end multitable
@node Zdiff
@chapter Zdiff
@cindex zdiff
zdiff compares two files and, if they differ, writes to standard output the
differences line by line. A hyphen @samp{-} used as a @var{file} argument
means standard input. If any file given is compressed, its decompressed
content is used. zdiff is a front end to the program diff and has the
limitation that messages from diff refer to temporary file names instead of
those specified.
@command{zdiff} compares two files and, if they differ, writes to standard
output the differences line by line. A hyphen @samp{-} used as a @var{file}
argument means standard input. If any file given is compressed, its
decompressed content is used. @command{zdiff} is a front end to the program
diff and has the limitation that messages from diff refer to temporary file
names instead of those specified.
The format for running zdiff is:
The format for running @command{zdiff} is:
@example
zdiff [@var{options}] @var{file1} [@var{file2}]
@ -433,7 +480,7 @@ zdiff [@var{options}] @var{file1} [@var{file2}]
@noindent
This compares @var{file1} to @var{file2}. The standard input is used only if
@var{file1} or @var{file2} refers to standard input. If @var{file2} is
omitted zdiff tries the following:
omitted @command{zdiff} tries the following:
@itemize -
@item
@ -449,8 +496,8 @@ contents of @var{file1}.[lz|bz2|gz|zst|xz] (the first one that is found).
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):
@command{zdiff} supports the following options (some options only work if
the diff program used supports them):
@table @code
@item -a
@ -465,7 +512,7 @@ Ignore changes in the amount of white space.
@itemx --ignore-blank-lines
Ignore changes whose lines are all blank.
@itemx -c
@item -c
Use the context output format.
@item -C @var{n}
@ -489,10 +536,11 @@ Ignore case differences in file contents.
Force the compressed formats given. Any of @var{format1} or @var{format2}
may be omitted and the corresponding format will be automatically detected.
Valid values for @var{format} are @samp{bz2}, @samp{gz}, @samp{lz},
@samp{xz}, and @samp{zst}. 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.
@samp{xz}, @samp{zst}, and @samp{un} for @samp{uncompressed}. If at least
one format is specified with this option, the file is passed to the
corresponding decompressor (or transmitted unmodified) without verifying its
format, and the exact file names of both @var{file1} and @var{file2} must be
given. Other names won't be tried.
@item -p
@itemx --show-c-function
@ -523,8 +571,8 @@ Same as -u but use @var{n} lines of context.
@item -v
@itemx --verbose
When specified before @samp{--version}, print the version of the diff
program used.
When specified before @option{--version}, print the version of the diff
program used. Further -v's increase the verbosity level. @xref{version}.
@item -w
@itemx --ignore-all-space
@ -546,12 +594,12 @@ Use the side by side output format.
@chapter Zgrep
@cindex zgrep
zgrep is a front end to the program grep that allows transparent search
on any combination of compressed and uncompressed files. If any file
given is compressed, its decompressed content is used. If a file given
does not exist, and its name does not end with one of the known
extensions, zgrep tries the compressed file names corresponding to the
formats supported. If a file fails to decompress, zgrep continues
@command{zgrep} is a front end to the program grep that allows transparent
search on any combination of compressed and uncompressed files. If any file
given is compressed, its decompressed content is used. If a file given does
not exist, and its name does not end with one of the known extensions,
@command{zgrep} tries the compressed file names corresponding to the formats
supported. If a file fails to decompress, @command{zgrep} continues
searching the rest of the files.
If a file is specified as @samp{-}, data are read from standard input,
@ -562,7 +610,14 @@ compressed 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:
For efficiency reasons, @command{zgrep} does not always read all its input.
For example, the shell command @w{@samp{base64 -d foo | zgrep -q X}} can
cause @command{zgrep} to exit immediately after reading a line containing
@samp{X}, without bothering to read the rest of its input data. This in turn
can cause base64 to exit with a nonzero status because base64 cannot write
to its output pipe after @command{zgrep} exits.
The format for running @command{zgrep} is:
@example
zgrep [@var{options}] @var{pattern} [@var{files}]
@ -572,9 +627,9 @@ zgrep [@var{options}] @var{pattern} [@var{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. Options -h, -H, -r, -R, and -Z are managed by
zgrep and not passed to grep):
@command{zgrep} supports the following options (Some options only work if
the grep program used supports them. Options -h, -H, -r, -R, and -Z are
managed by @command{zgrep} and not passed to grep):
@table @code
@item -a
@ -616,9 +671,9 @@ Interpret @var{pattern} as an extended regular expression (ERE).
@item -f @var{file}
@itemx --file=@var{file}
Obtain patterns from @var{file}, one per line.@*
When searching in several files at once, command substitution can be
used with @samp{-e} to read @var{file} only once, for example if
@var{file} is not a regular file:
When searching in several files at once, command substitution can be used
with @option{-e} to read @var{file} only once, for example if @var{file} is
not a regular file:
@w{@samp{zgrep -e "$(cat @var{file})" file1.lz file2.gz}}
@item -F
@ -648,11 +703,13 @@ Ignore binary files.
@item -l
@itemx --files-with-matches
Only print names of files containing at least one match.
Only print names of files containing at least one match. Stop reading each
file on the first match.
@item -L
@itemx --files-without-match
Only print names of files not containing any matches.@*
Only print names of files not containing any matches. Stop reading each file
on the first match.@*
Note: option -L fails (prints wrong results, returns wrong status, and even
hangs) when using GNU grep versions 3.2 to 3.4 inclusive because of a wrong
change in the exit status of grep, which was reverted in GNU grep 3.5.
@ -679,10 +736,11 @@ Show only the part of matching lines that actually matches @var{pattern}.
@item -O @var{format}
@itemx --force-format=@var{format}
Force the compressed format given. Valid values for @var{format} are
@samp{bz2}, @samp{gz}, @samp{lz}, @samp{xz}, and @samp{zst}. 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.
@samp{bz2}, @samp{gz}, @samp{lz}, @samp{xz}, @samp{zst}, and @samp{un} for
@samp{uncompressed}. If this option is used, the files are passed to the
corresponding decompressor (or transmitted unmodified) without verifying
their format, and the exact file name must be given. Other names won't be
tried.
@item -P
@itemx --perl-regexp
@ -724,8 +782,9 @@ Use binary I/O on platforms affected by the bug known as "text mode I/O".
Select non-matching lines.
@item --verbose
Verbose mode. Show error messages. When specified before @samp{--version},
print the version of the grep program used.
Verbose mode. Show error messages. When specified before @option{--version},
print the version of the grep program used. Repeating it increases the
verbosity level. @xref{version}.
@item -w
@itemx --word-regexp
@ -738,10 +797,10 @@ Match only whole lines.
@item -Z
@itemx --null
Output a zero byte (the ASCII NUL character) instead of the character that
normally follows a file name. For example, 'zgrep -lZ' outputs a zero byte
after each file name instead of the usual newline. This option makes the
output unambiguous, even in the presence of file names containing unusual
characters like newlines.
normally follows a file name. For example, @w{@samp{zgrep -lZ}} outputs a
zero byte after each file name instead of the usual newline. This option
makes the output unambiguous, even in the presence of file names containing
unusual characters like newlines.
@end table
@ -750,14 +809,16 @@ characters like newlines.
@chapter Ztest
@cindex ztest
ztest verifies the integrity of the compressed files specified.
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 compressed format. If
a file fails to decompress, does not exist, can't be opened, or is a
terminal, ztest continues verifying the rest of the files. A final
diagnostic is shown at verbosity level 1 or higher if any file fails the
test when testing multiple files.
@command{ztest} verifies the integrity of the compressed files specified. It
also warns if an uncompressed file has a compressed file name extension, or
if a compressed file has a wrong compressed extension. Uncompressed files
are otherwise ignored. If a file is specified as @samp{-}, the integrity of
compressed data read from standard input is verified. Data read from
standard input must be all in the same compressed format. If a file fails to
decompress, does not exist, can't be opened, or is a terminal, @command{ztest}
continues verifying the rest of the files. A final diagnostic is shown at
verbosity level 1 or higher if any file fails the test when testing multiple
files.
If no files are specified, recursive searches examine the current working
directory, and nonrecursive searches read standard input.
@ -776,18 +837,19 @@ 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:
The format for running @command{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.
Exit status is 0 if all compressed files verify OK, 1 if environmental
problems (file not found, invalid command line options, I/O errors, etc),
2 if any compressed file is corrupt or invalid, or if any file has an
incorrect file name extension.
ztest supports the following options:
@command{ztest} supports the following options:
@table @code
@item -O @var{format}
@ -815,8 +877,8 @@ 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.
Verbose mode. Show the verify status for each file processed. Further -v's
increase the verbosity level. @xref{version}.
@end table
@ -825,30 +887,30 @@ Further -v's increase the verbosity level.
@chapter Zupdate
@cindex zupdate
zupdate recompresses files from bzip2, gzip, xz, and zstd formats to lzip
format. Each original is compared with the new file and then deleted. Only
regular files with standard file name extensions are recompressed, other
files are ignored. Compressed files are decompressed and then recompressed
on the fly; no temporary files are created. If an error happens while
recompressing a file, 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.
@command{zupdate} recompresses files from bzip2, gzip, xz, and zstd formats
to lzip format. Each original is compared with the new file and then
deleted. Only regular files with standard file name extensions are
recompressed, other files are ignored. Compressed files are decompressed and
then recompressed on the fly; no temporary files are created. If an error
happens while recompressing a file, @command{zupdate} exits immediately
without recompressing the rest of the files. The lzip format is chosen as
destination because it is the most appropriate for long-term data archiving.
If no files are specified, recursive searches examine the current working
directory, and nonrecursive searches do nothing.
If the lzip compressed version of a file already exists, the file is
skipped unless the option @samp{--force} is given. In this case, if the
comparison with the existing lzip version fails, an error is returned
and the original file is not deleted. The operation of zupdate is meant
to be safe and not cause any data loss. Therefore, existing lzip
compressed files are never overwritten nor deleted.
If the lzip compressed version of a file already exists, the file is skipped
unless the option @option{--force} is given. In this case, if the comparison
with the existing lzip version fails, an error is returned and the original
file is not deleted. The operation of @command{zupdate} is meant to be safe
and not cause any data loss. Therefore, existing lzip compressed files are
never overwritten nor deleted.
Recompressing files from a read-only file system to another place can be
done by first linking the files from the destination directory and then
compressing the links: @w{@samp{ln -s /src/foo.gz . && zupdate foo.gz}}
Combining the options @samp{--force} and @samp{--keep}, as in
Combining the options @option{--force} and @option{--keep}, as in
@w{@samp{zupdate -f -k *.gz}}, verifies that there are no differences
between each pair of files in a multiformat set of files.
@ -857,20 +919,20 @@ The names of the original files must have one of the following extensions:@*
recompressed to @samp{.lz};@*
@samp{.tbz}, @samp{.tbz2}, @samp{.tgz}, @samp{.txz}, or @samp{.tzst}, which
are recompressed to @samp{.tlz}.@*
Keeping the combined extensions (@samp{.tgz} --> @samp{.tlz}) may be useful
when recompressing Slackware packages, for example.
Keeping the combined extensions @w{(@samp{.tgz} --> @samp{.tlz})} may be
useful when recompressing Slackware packages, for example.
Bzip2, gzip, and lzip are the primary formats. Xz and zstd are optional. If
the decompressor for the xz or zstd formats is not found, the corresponding
files are ignored.
Recompressing a file is much like copying or moving it. Therefore zupdate
preserves the access and modification dates, permissions, and, if you have
appropriate privileges, ownership of the file just as @w{@samp{cp -p}} does.
(If the user ID or the group ID can't be duplicated, the file permission
bits S_ISUID and S_ISGID are cleared).
Recompressing a file is much like copying or moving it. Therefore
@command{zupdate} preserves the access and modification dates, permissions,
and, if you have appropriate privileges, ownership of the file just as
@w{@samp{cp -p}} does. (If the user ID or the group ID can't be duplicated,
the file permission bits S_ISUID and S_ISGID are cleared).
The format for running zupdate is:
The format for running @command{zupdate} is:
@example
zupdate [@var{options}] [@var{files}]
@ -880,12 +942,29 @@ zupdate [@var{options}] [@var{files}]
Exit status is 0 if all the compressed files were successfully recompressed
(if needed), compared, and deleted (if requested). 1 if a non-fatal error
occurred (file not found or not regular, or has invalid format, or can't be
deleted). 2 if a fatal error occurred (compressor can't be run, or
comparison fails).
deleted). 2 if a fatal error occurred (invalid command line options,
compressor can't be run, or comparison fails).
zupdate supports the following options:
@command{zupdate} supports the following options:
@table @code
@item -d @var{dir}
@itemx --destdir=@var{dir}
Write recompressed files to another directory, using @var{dir} as base
directory, instead of writing them in the same directory as the original
files. In recursive mode, this is done by replacing each directory specified
in the command line with @var{dir} to produce the recompressed file names.
For example, @w{@samp{zupdate -r -d @var{dir} ../a}} recompresses a file
named @file{../a/b/c.gz} to @file{@var{dir}/b/c.lz}. Regular files specified
in the command line are recompressed directly into @var{dir}. For example,
@w{@samp{zupdate -d @var{dir} ../a/b/c.gz}} writes the recompressed file to
@file{@var{dir}/c.lz}.
This option allows recompressing files from a read-only file system to
another place without the need to copy or link them to the destination
directory first. (Remember to use option @option{--keep} when recompressing
read-only files to avoid warnings about files that can't be deleted).
@item -e
@itemx --expand-extensions
Expand combined file name extensions; recompress @samp{.tbz}, @samp{.tbz2},
@ -894,7 +973,7 @@ Expand combined file name extensions; recompress @samp{.tbz}, @samp{.tbz2},
@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
@option{--force} compares the content of the input file with the content
of the existing lzip file and deletes the input file if both contents
are identical.
@ -908,10 +987,10 @@ Keep (don't delete) the input file after comparing it with the lzip file.
@item -l
@itemx --lzip-verbose
Pass one option @samp{-v} to the lzip compressor so that it shows the
Pass one option @option{-v} to the lzip compressor so that it shows the
compression ratio for each file processed. Using lzip 1.15 or newer, a
second @samp{-l} shows the progress of compression. Use it together with
@samp{-v} to see the name of the file.
second @option{-l} shows the progress of compression. Use it together with
@option{-v} to see the name of the file.
@item -q
@itemx --quiet
@ -930,13 +1009,30 @@ 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.
Verbose mode. Show the files being processed. A second @option{-v} also shows
the files being ignored and increases the verbosity level. @xref{version}.
@item -0 .. -9
Set the compression level of lzip. By default zupdate passes @samp{-9} to
lzip. Custom compression options can be passed to lzip with the option
@samp{--lz}. For example @w{@samp{--lz='lzip -9 -s64MiB'}}.
Set the compression level of lzip. By default @command{zupdate} passes
@option{-9} to lzip. Custom compression options can be passed to lzip with
the option @option{--lz}. For example @w{@option{--lz='lzip -9 -s64MiB'}}.
@anchor{lz-compressor}
@item --lz=@var{command}
Set compression command. @var{command} may include arguments. For example
@w{@option{--lz='plzip --threads=2'}}. The name of the program can't begin
with @samp{-}. This option overrides the value set in @file{zutils.conf}.
The compression program used does not need to implement decompression
(@pxref{compressor-requirements}), but it must implement at least the
compression level option @option{-9} and the option @w{@option{-o @var{file}}}
to write the compressed output to @var{file}.
@uref{http://www.nongnu.org/lzip/manual/tarlz_manual.html,,tarlz} meets
these requirements, and therefore can be used to recompress POSIX tar
archives by using a command like
@w{@samp{zupdate --lz='tarlz -9 -z --no-solid' archive.tar.gz}}.
@ifnothtml
@xref{Top,tarlz manual,,tarlz}.
@end ifnothtml
@end table