Adding upstream version 1.13.upstream/1.13upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

8 files changed, 2808 insertions, 0 deletions

diff --git a/doc/zcat.1 b/doc/zcat.1
new file mode 100644
index 0000000..a27254b
--- /dev/null
+++ b/doc/zcat.1
@@ -0,0 +1,121 @@
+.\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.49.2.
+.TH ZCAT "1" "January 2024" "zutils 1.13" "User Commands"
+.SH NAME
+zcat \- decompress and concatenate files to standard output
+.SH SYNOPSIS
+.B zcat
+[\fI\,options\/\fR] [\fI\,files\/\fR]
+.SH DESCRIPTION
+zcat copies each 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 until one is found. If a file fails to decompress, zcat
+continues copying the rest of the files.
+.PP
+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 compressed format.
+.PP
+If no files are specified, recursive searches examine the current
+working directory, and nonrecursive searches read standard input.
+.PP
+The formats supported are bzip2, gzip, lzip, xz, and zstd.
+.PP
+Exit status is 0 if no errors occurred, 1 otherwise.
+.SH OPTIONS
+.TP
+\fB\-h\fR, \fB\-\-help\fR
+display this help and exit
+.TP
+\fB\-V\fR, \fB\-\-version\fR
+output version information and exit
+.TP
+\fB\-A\fR, \fB\-\-show\-all\fR
+equivalent to '\-vET'
+.TP
+\fB\-b\fR, \fB\-\-number\-nonblank\fR
+number nonblank output lines
+.TP
+\fB\-e\fR
+equivalent to '\-vE'
+.TP
+\fB\-E\fR, \fB\-\-show\-ends\fR
+display '$' at end of each line
+.TP
+\fB\-M\fR, \fB\-\-format=\fR<list>
+process only the formats in <list>
+.TP
+\fB\-n\fR, \fB\-\-number\fR
+number all output lines
+.TP
+\fB\-N\fR, \fB\-\-no\-rcfile\fR
+don't read runtime configuration file
+.TP
+\fB\-O\fR, \fB\-\-force\-format=\fR<fmt>
+force the input format
+.TP
+\fB\-q\fR, \fB\-\-quiet\fR
+suppress all messages
+.TP
+\fB\-r\fR, \fB\-\-recursive\fR
+operate recursively on directories
+.TP
+\fB\-R\fR, \fB\-\-dereference\-recursive\fR
+recursively follow symbolic links
+.TP
+\fB\-s\fR, \fB\-\-squeeze\-blank\fR
+never more than one single blank line
+.TP
+\fB\-t\fR
+equivalent to '\-vT'
+.TP
+\fB\-T\fR, \fB\-\-show\-tabs\fR
+display TAB characters as '^I'
+.TP
+\fB\-v\fR, \fB\-\-show\-nonprinting\fR
+use '^' and 'M\-' notation, except for LF and TAB
+.TP
+\fB\-\-verbose\fR
+verbose mode (show error messages)
+.TP
+\fB\-\-bz2=\fR<command>
+set compressor and options for bzip2 format
+.TP
+\fB\-\-gz=\fR<command>
+set compressor and options for gzip format
+.TP
+\fB\-\-lz=\fR<command>
+set compressor and options for lzip format
+.TP
+\fB\-\-xz=\fR<command>
+set compressor and options for xz format
+.TP
+\fB\-\-zst=\fR<command>
+set compressor and options for zstd format
+.PP
+Valid formats for options '\-M' and '\-O' are 'bz2', 'gz', 'lz', 'xz', 'zst',
+and 'un' for uncompressed.
+.SH "REPORTING BUGS"
+Report bugs to zutils\-bug@nongnu.org
+.br
+Zutils home page: http://www.nongnu.org/zutils/zutils.html
+.SH COPYRIGHT
+Copyright \(co 2024 Antonio Diaz Diaz.
+License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>
+.br
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+.SH "SEE ALSO"
+The full documentation for
+.B zcat
+is maintained as a Texinfo manual.  If the
+.B info
+and
+.B zcat
+programs are properly installed at your site, the command
+.IP
+.B info zutils
+.PP
+should give you access to the complete manual.
diff --git a/doc/zcmp.1 b/doc/zcmp.1
new file mode 100644
index 0000000..09af2a5
--- /dev/null
+++ b/doc/zcmp.1
@@ -0,0 +1,108 @@
+.\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.49.2.
+.TH ZCMP "1" "January 2024" "zutils 1.13" "User Commands"
+.SH NAME
+zcmp \- decompress and compare two files byte by byte
+.SH SYNOPSIS
+.B zcmp
+[\fI\,options\/\fR] \fI\,file1 \/\fR[\fI\,file2\/\fR]
+.SH DESCRIPTION
+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 '\-' used as a 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.
+.PP
+The formats supported are bzip2, gzip, lzip, xz, and zstd.
+.PP
+zcmp compares file1 to file2. The standard input is used only if file1 or
+file2 refers to standard input. If file2 is omitted zcmp tries to compare
+file1 with the corresponding uncompressed file (if file1 is compressed), and
+then with the corresponding compressed files of the remaining formats until
+one is found.
+.PP
+Exit status is 0 if inputs are identical, 1 if different, 2 if trouble.
+.SH OPTIONS
+.TP
+\fB\-h\fR, \fB\-\-help\fR
+display this help and exit
+.TP
+\fB\-V\fR, \fB\-\-version\fR
+output version information and exit
+.TP
+\fB\-b\fR, \fB\-\-print\-bytes\fR
+print differing bytes
+.TP
+\fB\-H\fR, \fB\-\-hexadecimal\fR
+print hexadecimal values instead of octal
+.TP
+\fB\-i\fR, \fB\-\-ignore\-initial=\fR<n>[:<n2>]
+ignore differences in the first <n> bytes
+.TP
+\fB\-l\fR, \fB\-\-list\fR
+list position, value of all differing bytes
+.TP
+\fB\-M\fR, \fB\-\-format=\fR<list>
+process only the formats in <list>
+.TP
+\fB\-n\fR, \fB\-\-bytes=\fR<n>
+compare at most <n> bytes
+.TP
+\fB\-N\fR, \fB\-\-no\-rcfile\fR
+don't read runtime configuration file
+.TP
+\fB\-O\fR, \fB\-\-force\-format\fR=\fI\,[\/\fR<f1>][,<f2>]
+force one or both input formats
+.TP
+\fB\-q\fR, \fB\-\-quiet\fR, \fB\-\-silent\fR
+suppress diagnostics written to stderr
+.TP
+\fB\-s\fR, \fB\-\-script\fR
+suppress messages about file differences
+.TP
+\fB\-v\fR, \fB\-\-verbose\fR
+verbose mode (opposite of \fB\-\-quiet\fR)
+.TP
+\fB\-\-bz2=\fR<command>
+set compressor and options for bzip2 format
+.TP
+\fB\-\-gz=\fR<command>
+set compressor and options for gzip format
+.TP
+\fB\-\-lz=\fR<command>
+set compressor and options for lzip format
+.TP
+\fB\-\-xz=\fR<command>
+set compressor and options for xz format
+.TP
+\fB\-\-zst=\fR<command>
+set compressor and options for zstd format
+.PP
+Valid formats for options '\-M' and '\-O' are 'bz2', 'gz', 'lz', 'xz', 'zst',
+and 'un' for uncompressed.
+.PP
+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: k = kB = 10^3 = 1000,
+Ki = KiB = 2^10 = 1024, M = 10^6, Mi = 2^20, G = 10^9, Gi = 2^30, etc.
+.SH "REPORTING BUGS"
+Report bugs to zutils\-bug@nongnu.org
+.br
+Zutils home page: http://www.nongnu.org/zutils/zutils.html
+.SH COPYRIGHT
+Copyright \(co 2024 Antonio Diaz Diaz.
+License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>
+.br
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+.SH "SEE ALSO"
+The full documentation for
+.B zcmp
+is maintained as a Texinfo manual.  If the
+.B info
+and
+.B zcmp
+programs are properly installed at your site, the command
+.IP
+.B info zutils
+.PP
+should give you access to the complete manual.
diff --git a/doc/zdiff.1 b/doc/zdiff.1
new file mode 100644
index 0000000..bbcdc94
--- /dev/null
+++ b/doc/zdiff.1
@@ -0,0 +1,139 @@
+.\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.49.2.
+.TH ZDIFF "1" "January 2024" "zutils 1.13" "User Commands"
+.SH NAME
+zdiff \- decompress and compare two files line by line
+.SH SYNOPSIS
+.B zdiff
+[\fI\,options\/\fR] \fI\,file1 \/\fR[\fI\,file2\/\fR]
+.SH DESCRIPTION
+zdiff compares two files and, if they differ, writes to standard output the
+differences line by line. A hyphen '\-' used as a 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.
+.PP
+\&'zdiff \fB\-v\fR \fB\-V\fR' prints the version of the diff program used.
+.PP
+The formats supported are bzip2, gzip, lzip, xz, and zstd.
+.PP
+zdiff compares file1 to file2. The standard input is used only if file1 or
+file2 refers to standard input. If file2 is omitted zdiff tries to compare
+file1 with the corresponding uncompressed file (if file1 is compressed), and
+then with the corresponding compressed files of the remaining formats until
+one is found.
+.PP
+Exit status is 0 if inputs are identical, 1 if different, 2 if trouble.
+Some options only work if the diff program used supports them.
+.SH OPTIONS
+.TP
+\fB\-h\fR, \fB\-\-help\fR
+display this help and exit
+.TP
+\fB\-V\fR, \fB\-\-version\fR
+output version information and exit
+.TP
+\fB\-a\fR, \fB\-\-text\fR
+treat all files as text
+.TP
+\fB\-b\fR, \fB\-\-ignore\-space\-change\fR
+ignore changes in the amount of white space
+.TP
+\fB\-B\fR, \fB\-\-ignore\-blank\-lines\fR
+ignore changes whose lines are all blank
+.TP
+\fB\-c\fR
+use the context output format
+.TP
+\fB\-C\fR, \fB\-\-context=\fR<n>
+same as \fB\-c\fR but use <n> lines of context
+.TP
+\fB\-d\fR, \fB\-\-minimal\fR
+try hard to find a smaller set of changes
+.TP
+\fB\-E\fR, \fB\-\-ignore\-tab\-expansion\fR
+ignore changes due to tab expansion
+.TP
+\fB\-i\fR, \fB\-\-ignore\-case\fR
+ignore case differences
+.TP
+\fB\-M\fR, \fB\-\-format=\fR<list>
+process only the formats in <list>
+.TP
+\fB\-N\fR, \fB\-\-no\-rcfile\fR
+don't read runtime configuration file
+.TP
+\fB\-O\fR, \fB\-\-force\-format\fR=\fI\,[\/\fR<f1>][,<f2>]
+force one or both input formats
+.TP
+\fB\-p\fR, \fB\-\-show\-c\-function\fR
+show which C function each change is in
+.TP
+\fB\-q\fR, \fB\-\-brief\fR
+output only whether files differ
+.TP
+\fB\-s\fR, \fB\-\-report\-identical\-files\fR
+report when two files are identical
+.TP
+\fB\-t\fR, \fB\-\-expand\-tabs\fR
+expand tabs to spaces in output
+.TP
+\fB\-T\fR, \fB\-\-initial\-tab\fR
+make tabs line up by prepending a tab
+.TP
+\fB\-u\fR
+use the unified output format
+.TP
+\fB\-U\fR, \fB\-\-unified=\fR<n>
+same as \fB\-u\fR but use <n> lines of context
+.TP
+\fB\-v\fR, \fB\-\-verbose\fR
+verbose mode (for \fB\-\-version\fR)
+.TP
+\fB\-w\fR, \fB\-\-ignore\-all\-space\fR
+ignore all white space
+.TP
+\fB\-W\fR, \fB\-\-width=\fR<n>
+output at most <n> print columns (for \fB\-y\fR)
+.TP
+\fB\-y\fR, \fB\-\-side\-by\-side\fR
+output in two columns
+.TP
+\fB\-\-bz2=\fR<command>
+set compressor and options for bzip2 format
+.TP
+\fB\-\-gz=\fR<command>
+set compressor and options for gzip format
+.TP
+\fB\-\-lz=\fR<command>
+set compressor and options for lzip format
+.TP
+\fB\-\-xz=\fR<command>
+set compressor and options for xz format
+.TP
+\fB\-\-zst=\fR<command>
+set compressor and options for zstd format
+.PP
+Valid formats for options '\-M' and '\-O' are 'bz2', 'gz', 'lz', 'xz', 'zst',
+and 'un' for uncompressed.
+.SH "REPORTING BUGS"
+Report bugs to zutils\-bug@nongnu.org
+.br
+Zutils home page: http://www.nongnu.org/zutils/zutils.html
+.SH COPYRIGHT
+Copyright \(co 2024 Antonio Diaz Diaz.
+License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>
+.br
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+.SH "SEE ALSO"
+The full documentation for
+.B zdiff
+is maintained as a Texinfo manual.  If the
+.B info
+and
+.B zdiff
+programs are properly installed at your site, the command
+.IP
+.B info zutils
+.PP
+should give you access to the complete manual.
diff --git a/doc/zgrep.1 b/doc/zgrep.1
new file mode 100644
index 0000000..605f1cb
--- /dev/null
+++ b/doc/zgrep.1
@@ -0,0 +1,194 @@
+.\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.49.2.
+.TH ZGREP "1" "January 2024" "zutils 1.13" "User Commands"
+.SH NAME
+zgrep \- search compressed files for a regular expression
+.SH SYNOPSIS
+.B zgrep
+[\fI\,options\/\fR] \fI\,<pattern> \/\fR[\fI\,files\/\fR]
+.SH DESCRIPTION
+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 until one is found. If a file fails to decompress, zgrep
+continues searching the rest of the files.
+.PP
+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
+compressed format.
+.PP
+If no files are specified, recursive searches examine the current
+working directory, and nonrecursive searches read standard input.
+.PP
+\&'zgrep \fB\-\-verbose\fR \fB\-V\fR' prints the version of the grep program used.
+.PP
+The formats supported are bzip2, gzip, lzip, xz, and zstd.
+.PP
+Exit status is 0 if match, 1 if no match, 2 if trouble.
+Some options only work if the grep program used supports them.
+.SH OPTIONS
+.TP
+\fB\-\-help\fR
+display this help and exit
+.TP
+\fB\-V\fR, \fB\-\-version\fR
+output version information and exit
+.TP
+\fB\-a\fR, \fB\-\-text\fR
+treat all files as text
+.TP
+\fB\-A\fR, \fB\-\-after\-context=\fR<n>
+print <n> lines of trailing context
+.TP
+\fB\-b\fR, \fB\-\-byte\-offset\fR
+print the byte offset of each line
+.TP
+\fB\-B\fR, \fB\-\-before\-context=\fR<n>
+print <n> lines of leading context
+.TP
+\fB\-c\fR, \fB\-\-count\fR
+only print a count of matching lines per file
+.TP
+\fB\-C\fR, \fB\-\-context=\fR<n>
+print <n> lines of output context
+.TP
+\fB\-\-color[=\fR<when>]
+show matched strings in color
+.TP
+\fB\-e\fR, \fB\-\-regexp=\fR<pattern>
+use <pattern> as the pattern to match
+.TP
+\fB\-E\fR, \fB\-\-extended\-regexp\fR
+<pattern> is an extended regular expression
+.TP
+\fB\-f\fR, \fB\-\-file=\fR<file>
+obtain patterns from <file>
+.TP
+\fB\-F\fR, \fB\-\-fixed\-strings\fR
+<pattern> is a set of newline\-separated strings
+.TP
+\fB\-G\fR, \fB\-\-basic\-regexp\fR
+<pattern> is a basic regular expression (default)
+.TP
+\fB\-h\fR, \fB\-\-no\-filename\fR
+suppress the prefixing file name on output
+.TP
+\fB\-H\fR, \fB\-\-with\-filename\fR
+print the file name for each match
+.TP
+\fB\-i\fR, \fB\-\-ignore\-case\fR
+ignore case distinctions
+.TP
+\fB\-I\fR
+ignore binary files
+.TP
+\fB\-l\fR, \fB\-\-files\-with\-matches\fR
+only print names of files containing matches
+.TP
+\fB\-L\fR, \fB\-\-files\-without\-match\fR
+only print names of files containing no matches
+.TP
+\fB\-\-label=\fR<label>
+use <label> as file name for standard input
+.TP
+\fB\-\-line\-buffered\fR
+flush output on every line
+.TP
+\fB\-m\fR, \fB\-\-max\-count=\fR<n>
+stop after <n> matches
+.TP
+\fB\-M\fR, \fB\-\-format=\fR<list>
+process only the formats in <list>
+.TP
+\fB\-n\fR, \fB\-\-line\-number\fR
+print the line number of each line
+.TP
+\fB\-N\fR, \fB\-\-no\-rcfile\fR
+don't read runtime configuration file
+.TP
+\fB\-o\fR, \fB\-\-only\-matching\fR
+show only the part of a line matching <pattern>
+.TP
+\fB\-O\fR, \fB\-\-force\-format=\fR<fmt>
+force the input format
+.TP
+\fB\-P\fR, \fB\-\-perl\-regexp\fR
+<pattern> is a Perl regular expression
+.TP
+\fB\-q\fR, \fB\-\-quiet\fR, \fB\-\-silent\fR
+suppress all messages
+.TP
+\fB\-r\fR, \fB\-\-recursive\fR
+operate recursively on directories
+.TP
+\fB\-R\fR, \fB\-\-dereference\-recursive\fR
+recursively follow symbolic links
+.TP
+\fB\-s\fR, \fB\-\-no\-messages\fR
+suppress error messages
+.TP
+\fB\-T\fR, \fB\-\-initial\-tab\fR
+make tabs line up (if needed)
+.TP
+\fB\-U\fR, \fB\-\-binary\fR
+don't strip CR characters at EOL (DOS/Windows)
+.TP
+\fB\-v\fR, \fB\-\-invert\-match\fR
+select non\-matching lines
+.TP
+\fB\-\-verbose\fR
+verbose mode (show error messages)
+.TP
+\fB\-w\fR, \fB\-\-word\-regexp\fR
+match only whole words
+.TP
+\fB\-x\fR, \fB\-\-line\-regexp\fR
+match only whole lines
+.TP
+\fB\-Z\fR, \fB\-\-null\fR
+print 0 byte (ASCII NUL) after file name
+.TP
+\fB\-\-bz2=\fR<command>
+set compressor and options for bzip2 format
+.TP
+\fB\-\-gz=\fR<command>
+set compressor and options for gzip format
+.TP
+\fB\-\-lz=\fR<command>
+set compressor and options for lzip format
+.TP
+\fB\-\-xz=\fR<command>
+set compressor and options for xz format
+.TP
+\fB\-\-zst=\fR<command>
+set compressor and options for zstd format
+.PP
+Valid formats for options '\-M' and '\-O' are 'bz2', 'gz', 'lz', 'xz', 'zst',
+and 'un' for uncompressed.
+.PP
+Numbers may be followed by a multiplier: k = kB = 10^3 = 1000,
+Ki = KiB = 2^10 = 1024, M = 10^6, Mi = 2^20, G = 10^9, Gi = 2^30, etc...
+.SH "REPORTING BUGS"
+Report bugs to zutils\-bug@nongnu.org
+.br
+Zutils home page: http://www.nongnu.org/zutils/zutils.html
+.SH COPYRIGHT
+Copyright \(co 2024 Antonio Diaz Diaz.
+License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>
+.br
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+.SH "SEE ALSO"
+The full documentation for
+.B zgrep
+is maintained as a Texinfo manual.  If the
+.B info
+and
+.B zgrep
+programs are properly installed at your site, the command
+.IP
+.B info zutils
+.PP
+should give you access to the complete manual.
diff --git a/doc/ztest.1 b/doc/ztest.1
new file mode 100644
index 0000000..caa0b2a
--- /dev/null
+++ b/doc/ztest.1
@@ -0,0 +1,102 @@
+.\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.49.2.
+.TH ZTEST "1" "January 2024" "zutils 1.13" "User Commands"
+.SH NAME
+ztest \- check the integrity of compressed files
+.SH SYNOPSIS
+.B ztest
+[\fI\,options\/\fR] [\fI\,files\/\fR]
+.SH DESCRIPTION
+ztest checks 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 '\-', the integrity of
+compressed data read from standard input is checked. 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 testing 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.
+.PP
+If no files are specified, recursive searches examine the current
+working directory, and nonrecursive searches read standard input.
+.PP
+The formats supported are bzip2, gzip, lzip, xz, and zstd.
+.PP
+Note that error detection in the xz format is broken. First, some xz files
+lack integrity information. Second, not all xz decompressors can check 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 checked as
+reliably as files in the other formats can.
+.PP
+Exit status is 0 if all compressed files check 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.
+.SH OPTIONS
+.TP
+\fB\-h\fR, \fB\-\-help\fR
+display this help and exit
+.TP
+\fB\-V\fR, \fB\-\-version\fR
+output version information and exit
+.TP
+\fB\-M\fR, \fB\-\-format=\fR<list>
+process only the formats in <list>
+.TP
+\fB\-N\fR, \fB\-\-no\-rcfile\fR
+don't read runtime configuration file
+.TP
+\fB\-O\fR, \fB\-\-force\-format=\fR<fmt>
+force the input format
+.TP
+\fB\-q\fR, \fB\-\-quiet\fR
+suppress all messages
+.TP
+\fB\-r\fR, \fB\-\-recursive\fR
+operate recursively on directories
+.TP
+\fB\-R\fR, \fB\-\-dereference\-recursive\fR
+recursively follow symbolic links
+.TP
+\fB\-v\fR, \fB\-\-verbose\fR
+be verbose (a 2nd \fB\-v\fR gives more)
+.TP
+\fB\-\-bz2=\fR<command>
+set compressor and options for bzip2 format
+.TP
+\fB\-\-gz=\fR<command>
+set compressor and options for gzip format
+.TP
+\fB\-\-lz=\fR<command>
+set compressor and options for lzip format
+.TP
+\fB\-\-xz=\fR<command>
+set compressor and options for xz format
+.TP
+\fB\-\-zst=\fR<command>
+set compressor and options for zstd format
+.PP
+Valid formats for options '\-M' and '\-O' are 'bz2', 'gz', 'lz', 'xz', and 'zst'.
+.SH "REPORTING BUGS"
+Report bugs to zutils\-bug@nongnu.org
+.br
+Zutils home page: http://www.nongnu.org/zutils/zutils.html
+.SH COPYRIGHT
+Copyright \(co 2024 Antonio Diaz Diaz.
+License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>
+.br
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+.SH "SEE ALSO"
+The full documentation for
+.B ztest
+is maintained as a Texinfo manual.  If the
+.B info
+and
+.B ztest
+programs are properly installed at your site, the command
+.IP
+.B info zutils
+.PP
+should give you access to the complete manual.
diff --git a/doc/zupdate.1 b/doc/zupdate.1
new file mode 100644
index 0000000..c50a2df
--- /dev/null
+++ b/doc/zupdate.1
@@ -0,0 +1,122 @@
+.\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.49.2.
+.TH ZUPDATE "1" "January 2024" "zutils 1.13" "User Commands"
+.SH NAME
+zupdate \- recompress bzip2, gzip, xz, zstd files to lzip format
+.SH SYNOPSIS
+.B zupdate
+[\fI\,options\/\fR] [\fI\,files\/\fR]
+.SH DESCRIPTION
+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. The lzip format
+is chosen as destination because it is the most appropriate for
+long\-term archiving.
+.PP
+If no files are specified, recursive searches examine the current
+working directory, and nonrecursive searches do nothing.
+.PP
+If the lzip\-compressed version of a file already exists, the file is skipped
+unless the 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 zupdate is meant to be safe and not cause
+any data loss. Therefore, existing lzip\-compressed files are never
+overwritten nor deleted.
+.PP
+The names of the original files must have one of the following extensions:
+.PP
+\&'.bz2', '.gz', '.xz', '.zst', or '.Z', which are recompressed to '.lz'.
+.PP
+\&'.tbz', '.tbz2', '.tgz', '.txz', or '.tzst', which are recompressed to '.tlz'.
+.PP
+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 (invalid command\-line options,
+compressor can't be run, or comparison fails).
+.SH OPTIONS
+.TP
+\fB\-h\fR, \fB\-\-help\fR
+display this help and exit
+.TP
+\fB\-V\fR, \fB\-\-version\fR
+output version information and exit
+.TP
+\fB\-d\fR, \fB\-\-destdir=\fR<dir>
+write recompressed files into <dir>
+.TP
+\fB\-e\fR, \fB\-\-expand\-extensions\fR
+expand combined extensions; tgz \fB\-\-\fR> tar.lz
+.TP
+\fB\-f\fR, \fB\-\-force\fR
+don't skip a file even if the .lz exists
+.TP
+\fB\-i\fR, \fB\-\-ignore\-errors\fR
+ignore non\-fatal errors
+.TP
+\fB\-k\fR, \fB\-\-keep\fR
+keep (don't delete) input files
+.TP
+\fB\-l\fR, \fB\-\-lzip\-verbose\fR
+pass one option \fB\-v\fR to the lzip compressor
+.TP
+\fB\-M\fR, \fB\-\-format=\fR<list>
+process only the formats in <list>
+.TP
+\fB\-N\fR, \fB\-\-no\-rcfile\fR
+don't read runtime configuration file
+.TP
+\fB\-q\fR, \fB\-\-quiet\fR
+suppress all messages
+.TP
+\fB\-r\fR, \fB\-\-recursive\fR
+operate recursively on directories
+.TP
+\fB\-R\fR, \fB\-\-dereference\-recursive\fR
+recursively follow symbolic links
+.TP
+\fB\-v\fR, \fB\-\-verbose\fR
+be verbose (a 2nd \fB\-v\fR gives more)
+.TP
+\fB\-0\fR .. \fB\-9\fR
+set compression level [default 9]
+.TP
+\fB\-\-bz2=\fR<command>
+set compressor and options for bzip2 format
+.TP
+\fB\-\-gz=\fR<command>
+set compressor and options for gzip format
+.TP
+\fB\-\-lz=\fR<command>
+set compressor and options for lzip format
+.TP
+\fB\-\-xz=\fR<command>
+set compressor and options for xz format
+.TP
+\fB\-\-zst=\fR<command>
+set compressor and options for zstd format
+.PP
+Valid formats for option '\-M' are 'bz2', 'gz', 'lz', 'xz', and 'zst'.
+.SH "REPORTING BUGS"
+Report bugs to zutils\-bug@nongnu.org
+.br
+Zutils home page: http://www.nongnu.org/zutils/zutils.html
+.SH COPYRIGHT
+Copyright \(co 2024 Antonio Diaz Diaz.
+License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>
+.br
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
+.SH "SEE ALSO"
+The full documentation for
+.B zupdate
+is maintained as a Texinfo manual.  If the
+.B info
+and
+.B zupdate
+programs are properly installed at your site, the command
+.IP
+.B info zutils
+.PP
+should give you access to the complete manual.
diff --git a/doc/zutils.info b/doc/zutils.info
new file mode 100644
index 0000000..d7f9cb4
--- /dev/null
+++ b/doc/zutils.info
@@ -0,0 +1,988 @@
+This is zutils.info, produced by makeinfo version 4.13+ from zutils.texi.
+
+INFO-DIR-SECTION 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 1.13, 23 January 2024).
+
+* Menu:
+
+* Introduction::        Purpose and features of zutils
+* Common options::      Options common to all utilities
+* Configuration::       The configuration file zutils.conf
+* 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) 2009-2024 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 file given,
+including standard input, is compressed, its decompressed content is used.
+Compressed files are decompressed on the fly; no temporary files are
+created. Data format is detected by its identifier string (magic bytes), not
+by the file name extension. Empty files are considered uncompressed.
+
+   These utilities are not wrapper scripts but safer and more efficient C++
+programs. In particular the option '--recursive' is very efficient in those
+utilities supporting it.
+
+The utilities provided are 'zcat', 'zcmp', 'zdiff', 'zgrep', 'ztest', and
+'zupdate'.
+The formats supported are bzip2, gzip, 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.
+
+   When 'zcat', 'zcmp', 'zdiff', or 'zgrep' need to try compressed file
+names, the search order is: lzip, gzip, bzip2, zstd, xz.
+(FILE.[lz|gz|bz2|zst|xz]).
+
+   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. Zstd currently does
+not even document its exit status in its man page. *Note
+compressor-requirements::.
+
+   FORMAT NOTE 1: The 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 'foo' in gzip
+and lzip files only: 'zgrep foo -r --format=gz,lz somedir somefile.tar'.
+
+   FORMAT NOTE 2: The standard POSIX compress format (.Z) is obsolete and is
+only supported through gzip. For this to work, the gzip program used (for
+example GNU gzip) must be able to decompress .Z files.
+
+   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.
+
+
+File: zutils.info,  Node: Common options,  Next: Configuration,  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. Remember to prepend './' to any file name beginning with a hyphen, or
+use '--'. *Note Argument syntax: (arg_parser)Argument syntax.
+
+'-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. 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. At verbosity level 1 (2 for 'zdiff' and 'zgrep') or
+     higher, print also the versions of the compressors used (perhaps
+     limited by option '--format'). (The compressors used must support the
+     option '-V' for this to work).
+
+'-M FORMAT_LIST'
+'--format=FORMAT_LIST'
+     Process only the formats listed in the comma-separated FORMAT_LIST.
+     Valid formats are 'bz2', 'gz', 'lz', 'xz', 'zst', 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 .Z
+     lz    enables   .lz .tlz
+     xz    enables   .xz .txz
+     zst   enables   .zst .tzst
+     un    enables   any other file name
+
+'-N'
+'--no-rcfile'
+     Don't read the runtime configuration file 'zutils.conf'.
+
+'--bz2=COMMAND'
+'--gz=COMMAND'
+'--lz=COMMAND'
+'--xz=COMMAND'
+'--zst=COMMAND'
+     Set program to be used as decompressor for the corresponding format.
+     COMMAND may include arguments. For example '--lz='plzip --threads=2''.
+     'zupdate' uses '--lz' for compression, not for decompression (*note
+     lz-compressor::). The name of the program can't begin with '-'. These
+     options override the values set in 'zutils.conf'. The compression
+     program used must meet three requirements:
+
+       1. When called with the option '-d' and without file names, it must
+          read compressed data from the standard input and produce
+          decompressed data on the standard output.
+
+       2. If the option '-q' 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.
+
+
+   Numbers 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 '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)
+R        ronnabyte  (10^27)         |   Ri       robibyte  (2^90)
+Q        quettabyte (10^30)         |   Qi       quebibyte (2^100)
+
+
+File: zutils.info,  Node: Configuration,  Next: Zcat,  Prev: Common options,  Up: Top
+
+3 The configuration file 'zutils.conf'
+**************************************
+
+'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.
+'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 'zutils.conf'.
+
+   You may copy the system 'zutils.conf' file '${sysconfdir}/zutils.conf'
+to '$XDG_CONFIG_HOME/zutils.conf' and customize these options as you like.
+('XDG_CONFIG_HOME' defaults to '$HOME/.config'). The file syntax is fairly
+obvious (and there are further instructions in it):
+
+  1. Any line beginning with '#' is a comment line.
+
+  2. Each non-comment line defines the command to be used for the
+     corresponding format, with the syntax:
+          <format> = <compressor> [options]
+     where <format> is one of 'bz2', 'gz', 'lz', 'xz', or 'zst'.
+
+
+File: zutils.info,  Node: Zcat,  Next: Zcmp,  Prev: Configuration,  Up: Top
+
+4 Zcat
+******
+
+'zcat' copies each FILE argument to standard output in sequence. If any
+file given is compressed, its decompressed content is copied. If a file
+given does not exist, and its name does not end with one of the known
+extensions, 'zcat' tries the compressed file names corresponding to the
+formats supported until one is found. *Note search-order::. If a file fails
+to decompress, 'zcat' continues copying the rest of the files.
+
+   If a file is specified as '-', data are read from standard input,
+decompressed if needed, and sent to standard output. Data read from
+standard input must be of the same type; all uncompressed or all in the
+same compressed format.
+
+   If no files are specified, recursive searches examine the current working
+directory, and nonrecursive searches read standard input.
+
+   The format for running 'zcat' is:
+
+     zcat [OPTIONS] [FILES]
+
+Exit status is 0 if no errors occurred, 1 otherwise.
+
+   'zcat' supports the following options:
+
+'-A'
+'--show-all'
+     Equivalent to '-vET'.
+
+'-b'
+'--number-nonblank'
+     Number all nonblank output lines, starting with 1. The line count is
+     unlimited.
+
+'-e'
+     Equivalent to '-vE'.
+
+'-E'
+'--show-ends'
+     Print a '$' 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 compressed format given. Valid values for FORMAT are 'bz2',
+     'gz', 'lz', 'xz', 'zst', and 'un' for 'uncompressed'. If this option
+     is used, the files are passed to the corresponding decompressor (or
+     transmitted unmodified) without checking their format, and the exact
+     file name must be given. Other names are not tried.
+
+'-q'
+'--quiet'
+     Quiet operation. Suppress all messages.
+
+'-r'
+'--recursive'
+     For each directory operand, read and process all files in that
+     directory, recursively. Follow symbolic links given in the command
+     line, but skip symbolic links that are encountered recursively.
+
+'-R'
+'--dereference-recursive'
+     For each directory operand, read and process all files in that
+     directory, recursively, following all symbolic links.
+
+'-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. Repeating it increases the verbosity
+     level. *Note version::.
+
+
+
+File: zutils.info,  Node: Zcmp,  Next: Zdiff,  Prev: Zcat,  Up: Top
+
+5 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 '-' used as a 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:
+
+     zcmp [OPTIONS] FILE1 [FILE2]
+
+This compares FILE1 to FILE2. The standard input is used only if FILE1 or
+FILE2 refers to standard input. If FILE2 is omitted 'zcmp' tries to compare
+FILE1 with the corresponding uncompressed file (if FILE1 is compressed),
+and then with the corresponding compressed files of the remaining formats
+until one is found. *Note search-order::.
+
+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 values of the differing bytes (in octal by default) followed
+     by the bytes themselves in printable form. Print control bytes as a '^'
+     followed by a letter, and precede bytes larger than 127 with 'M-'
+     (which stands for "meta").
+
+'-H'
+'--hexadecimal'
+     Print the values of the differing bytes in hexadecimal instead of
+     octal.
+
+'-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'
+'--list'
+     Print the byte numbers (in decimal) and values (in octal by default)
+     of all differing bytes. Bytes are numbered starting with 1.
+
+'-n COUNT'
+'--bytes=COUNT'
+     Compare at most COUNT input bytes.
+
+'-O [FORMAT1][,FORMAT2]'
+'--force-format=[FORMAT1][,FORMAT2]'
+     Force the compressed formats given. If FORMAT1 or FORMAT2 is omitted,
+     the corresponding format is automatically detected. Valid values for
+     FORMAT are 'bz2', 'gz', 'lz', 'xz', 'zst', and 'un' for
+     'uncompressed'. If at least one format is specified with this option,
+     the file is passed to the corresponding decompressor (or transmitted
+     unmodified) without checking its format, and the exact file names of
+     both FILE1 and FILE2 must be given. Other names are not tried.
+
+'-q'
+'--quiet'
+'--silent'
+     Suppress diagnostics written to standard error, even the
+     'EOF on <name_of_shorter_file>' diagnostic. Byte differences are still
+     written to standard output. ('-q' produces no output except byte
+     differences).
+
+'-s'
+'--script'
+     Write nothing to standard output or standard error when files differ,
+     not even the '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. ('-s' produces
+     no output except error messages).
+
+'-v'
+'--verbose'
+     Verbose mode. Undoes the effect of '--quiet'. Further -v's increase
+     the verbosity level. *Note version::.
+
+
+
+File: zutils.info,  Node: Zdiff,  Next: Zgrep,  Prev: Zcmp,  Up: Top
+
+6 Zdiff
+*******
+
+'zdiff' compares two files and, if they differ, writes to standard output
+the differences line by line. A hyphen '-' used as a 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.
+
+   The format for running 'zdiff' is:
+
+     zdiff [OPTIONS] FILE1 [FILE2]
+
+This compares FILE1 to FILE2. The standard input is used only if FILE1 or
+FILE2 refers to standard input. If FILE2 is omitted 'zdiff' tries to
+compare FILE1 with the corresponding uncompressed file (if FILE1 is
+compressed), and then with the corresponding compressed files of the
+remaining formats until one is found. *Note search-order::.
+
+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. Consider uppercase and lowercase letters
+     equivalent.
+
+'-O [FORMAT1][,FORMAT2]'
+'--force-format=[FORMAT1][,FORMAT2]'
+     Force the compressed formats given. If FORMAT1 or FORMAT2 is omitted,
+     the corresponding format is automatically detected. Valid values for
+     FORMAT are 'bz2', 'gz', 'lz', 'xz', 'zst', and 'un' for
+     'uncompressed'. If at least one format is specified with this option,
+     the file is passed to the corresponding decompressor (or transmitted
+     unmodified) without checking its format, and the exact file names of
+     both FILE1 and FILE2 must be given. Other names are not 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.
+
+'-v'
+'--verbose'
+     When specified before '--version', print the version of the diff
+     program used. Further -v's increase the verbosity level. *Note
+     version::.
+
+'-w'
+'--ignore-all-space'
+     Ignore all white space.
+
+'-W COLUMNS'
+'--width=COLUMNS'
+     Output at most the specified number of print columns per line in side
+     by side format.
+
+'-y'
+'--side-by-side'
+     Use the side by side output format.
+
+
+
+File: zutils.info,  Node: Zgrep,  Next: Ztest,  Prev: Zdiff,  Up: Top
+
+7 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
+until one is found. *Note search-order::. If a file fails to decompress,
+'zgrep' continues searching the rest of the files.
+
+   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 compressed format.
+
+   If no files are specified, recursive searches examine the current working
+directory, and nonrecursive searches read standard input.
+
+   For efficiency reasons, 'zgrep' does not always read all its input. For
+example, the shell command 'base64 -d foo | zgrep -q X' can cause 'zgrep'
+to exit immediately after reading a line containing '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
+'zgrep' exits.
+
+   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. Options -h, -H, -r, -R, and -Z are managed
+by 'zgrep' and not passed to grep):
+
+'-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'
+     Interpret PATTERN as an extended regular expression (ERE).
+
+'-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'
+     Interpret PATTERN as a set of newline-separated strings.
+
+'-G'
+'--basic-regexp'
+     Interpret PATTERN as a basic regular expression (BRE). This is the
+     default.
+
+'-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. Stop reading
+     each file on the first match.
+
+'-L'
+'--files-without-match'
+     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.
+
+'--label=LABEL'
+     Display input actually coming from standard input as input coming from
+     file LABEL.
+
+'--line-buffered'
+     Use line buffering on output. This may cause a performance penalty.
+
+'-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 compressed format given. Valid values for FORMAT are 'bz2',
+     'gz', 'lz', 'xz', 'zst', and 'un' for 'uncompressed'. If this option
+     is used, the files are passed to the corresponding decompressor (or
+     transmitted unmodified) without checking their format, and the exact
+     file name must be given. Other names are not tried.
+
+'-P'
+'--perl-regexp'
+     Interpret PATTERN as a Perl-compatible regular expression (PCRE).
+
+'-q'
+'--quiet'
+'--silent'
+     Suppress all messages. Exit immediately with zero status if any match
+     is found, even if an error was detected.
+
+'-r'
+'--recursive'
+     For each directory operand, read and process all files in that
+     directory, recursively. Follow symbolic links given in the command
+     line, but skip symbolic links that are encountered recursively.
+
+'-R'
+'--dereference-recursive'
+     For each directory operand, read and process all files in that
+     directory, recursively, following all symbolic links.
+
+'-s'
+'--no-messages'
+     Suppress error messages about nonexistent or unreadable files.
+
+'-T'
+'--initial-tab'
+     Make sure that the first character of actual line content lies on a tab
+     stop, so that the alignment of tabs looks normal.
+
+'-U'
+'--binary'
+     Use binary I/O on platforms affected by the bug known as "text mode
+     I/O". (MS-DOS, MS-Windows, OS/2).
+
+'-v'
+'--invert-match'
+     Select non-matching lines.
+
+'--verbose'
+     Verbose mode. Show error messages. When specified before '--version',
+     print the version of the grep program used. Repeating it increases the
+     verbosity level. *Note version::.
+
+'-w'
+'--word-regexp'
+     Match only whole words.
+
+'-x'
+'--line-regexp'
+     Match only whole lines.
+
+'-Z'
+'--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.
+
+
+
+File: zutils.info,  Node: Ztest,  Next: Zupdate,  Prev: Zgrep,  Up: Top
+
+8 Ztest
+*******
+
+'ztest' checks 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 '-', the integrity of
+compressed data read from standard input is checked. 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 testing 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.
+
+   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.
+
+   Note that error detection in the xz format is broken. First, some xz
+files lack integrity information. Second, not all xz decompressors can
+check 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
+checked as reliably as files in the other formats can.
+
+   The format for running 'ztest' is:
+
+     ztest [OPTIONS] [FILES]
+
+Exit status is 0 if all compressed files check 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:
+
+'-O FORMAT'
+'--force-format=FORMAT'
+     Force the compressed format given. Valid values for FORMAT are 'bz2',
+     'gz', 'lz', 'xz', and 'zst'. If this option is used, the files are
+     passed to the corresponding decompressor without checking their
+     format, and any files in a format that the decompressor can't
+     understand fail the test.
+
+'-q'
+'--quiet'
+     Quiet operation. Suppress all messages.
+
+'-r'
+'--recursive'
+     For each directory operand, read and process all files in that
+     directory, recursively. Follow symbolic links given in the command
+     line, but skip symbolic links that are encountered recursively.
+
+'-R'
+'--dereference-recursive'
+     For each directory operand, read and process all files in that
+     directory, recursively, following all symbolic links.
+
+'-v'
+'--verbose'
+     Verbose mode. Show the check status for each file processed. Further
+     -v's increase the verbosity level. *Note version::.
+
+
+
+File: zutils.info,  Node: Zupdate,  Next: Problems,  Prev: Ztest,  Up: Top
+
+9 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 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 '--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.
+
+   Combining the options '--force' and '--keep', as in
+'zupdate -f -k *.gz', checks 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', '.gz', '.xz', '.zst', or '.Z', which are recompressed to '.lz';
+'.tbz', '.tbz2', '.tgz', '.txz', or '.tzst', which are recompressed to
+'.tlz'.
+Keeping the combined extensions ('.tgz' --> '.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 '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). 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 (invalid command-line options,
+compressor can't be run, or comparison fails).
+
+   'zupdate' supports the following options:
+
+'-d DIR'
+'--destdir=DIR'
+     Write recompressed files to another directory, using 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 DIR to produce the
+     recompressed file names. For example, 'zupdate -r -d DIR ../a'
+     recompresses a file named '../a/b/c.gz' to 'DIR/b/c.lz'. Regular files
+     specified in the command line are recompressed directly into DIR. For
+     example, 'zupdate -d DIR ../a/b/c.gz' writes the recompressed file to
+     '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 '--keep' when recompressing
+     read-only files to avoid warnings about files that can't be deleted).
+
+'-e'
+'--expand-extensions'
+     Expand combined file name extensions; recompress '.tbz', '.tbz2',
+     '.tgz', '.txz', and '.tzst' to 'tar.lz'.
+
+'-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.
+
+'-i'
+'--ignore-errors'
+     Ignore non-fatal errors. (See exit status above).
+
+'-k'
+'--keep'
+     Keep (don't delete) the input file after comparing it with the lzip
+     file. Use it when recompressing files from a read-only file system.
+     (See option '--destdir' above).
+
+'-l'
+'--lzip-verbose'
+     Pass one 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 '-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'
+     For each directory operand, read and process all files in that
+     directory, recursively. Follow symbolic links given in the command
+     line, but skip symbolic links that are encountered recursively.
+
+'-R'
+'--dereference-recursive'
+     For each directory operand, read and process all files in that
+     directory, recursively, following all symbolic links.
+
+'-v'
+'--verbose'
+     Verbose mode. Show the files being processed. A second '-v' also shows
+     the files being ignored and increases the verbosity level. *Note
+     version::.
+
+'-0 .. -9'
+     Set the compression level of lzip. By default 'zupdate' passes '-9' to
+     lzip. Custom compression options can be passed to lzip with the option
+     '--lz'. For example '--lz='lzip -9 -s64MiB''.
+
+'--lz=COMMAND'
+     Set compression command. COMMAND may include arguments. For example
+     '--lz='plzip --threads=2''. The name of the program can't begin with
+     '-'. This option overrides the value set in 'zutils.conf'. The
+     compression program used does not need to implement decompression
+     (*note compressor-requirements::), but it must implement at least the
+     compression level option '-9' and the option '-o FILE' to write the
+     compressed output to FILE. tarlz meets these requirements, and
+     therefore can be used to recompress POSIX tar archives by using a
+     command like 'zupdate --lz='tarlz -9 -z --no-solid' archive.tar.gz'.
+     *Note tarlz manual: (tarlz)Top.
+
+
+
+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
+*************
+
+
+* Menu:
+
+* bugs:                                  Problems.                  (line 6)
+* common options:                        Common options.            (line 6)
+* getting help:                          Problems.                  (line 6)
+* introduction:                          Introduction.              (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)
+* zutils.conf:                           Configuration.             (line 6)
+
+
+
+Tag Table:
+Node: Top217
+Node: Introduction1152
+Ref: search-order2304
+Node: Common options3461
+Ref: version4027
+Ref: compressor-requirements5978
+Node: Configuration7367
+Node: Zcat8400
+Node: Zcmp11139
+Node: Zdiff14407
+Node: Zgrep17490
+Node: Ztest23637
+Node: Zupdate26430
+Ref: lz-compressor31838
+Node: Problems32539
+Node: Concept index33073
+
+End Tag Table
+
+
+Local Variables:
+coding: iso-8859-15
+End:
diff --git a/doc/zutils.texi b/doc/zutils.texi
new file mode 100644
index 0000000..1646e7d
--- /dev/null
+++ b/doc/zutils.texi
@@ -0,0 +1,1034 @@
+\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 23 January 2024
+@set VERSION 1.13
+
+@dircategory 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
+
+@ifnottex
+@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
+* Configuration::       The configuration file zutils.conf
+* 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{} 2009-2024 Antonio Diaz Diaz.
+
+This manual is free documentation: you have unlimited permission to copy,
+distribute, and modify it.
+@end ifnottex
+
+
+@node Introduction
+@chapter Introduction
+@cindex introduction
+
+@uref{http://www.nongnu.org/zutils/zutils.html,,Zutils}
+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. Data format is detected by its identifier string (magic bytes), not
+by the file name extension. Empty files are considered uncompressed.
+
+These utilities are not wrapper scripts but safer and more efficient C++
+programs. In particular the option @option{--recursive} is very efficient in
+those utilities supporting it.
+
+@noindent
+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.
+
+@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.
+
+@anchor{search-order}
+When @command{zcat}, @command{zcmp}, @command{zdiff}, or @command{zgrep}
+need to try compressed file names, the search order is: lzip, gzip, bzip2,
+zstd, xz. (@var{file}.[lz|gz|bz2|zst|xz]).
+
+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. Zstd currently does
+not even document its exit status in its man page.
+@xref{compressor-requirements}.
+
+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:
+@w{@samp{zgrep foo -r --format=gz,lz somedir somefile.tar}}.
+
+FORMAT NOTE 2: The standard POSIX compress format (.Z) is obsolete and is
+only supported through gzip. For this to work, the gzip program used (for
+example GNU gzip) must be able to decompress .Z files.
+
+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.
+
+
+@node Common options
+@chapter Common options
+@cindex common options
+
+The following
+@uref{http://www.nongnu.org/arg-parser/manual/arg_parser_manual.html#Argument-syntax,,options}:
+are available in all the utilities. Rather than writing identical
+descriptions for each of the programs, they are described here. Remember to
+prepend @file{./} to any file name beginning with a hyphen, or use @samp{--}.
+@ifnothtml
+@xref{Argument syntax,,,arg_parser}.
+@end ifnothtml
+
+@table @code
+@item -h
+@itemx --help
+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, @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}
+Process only the formats listed in the comma-separated @var{format_list}.
+Valid formats are @samp{bz2}, @samp{gz}, @samp{lz}, @samp{xz}, @samp{zst},
+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 .Z
+@item lz  @tab enables @tab .lz .tlz
+@item xz  @tab enables @tab .xz .txz
+@item zst @tab enables @tab .zst .tzst
+@item un  @tab enables @tab any other file name
+@end multitable
+
+@item -N
+@itemx --no-rcfile
+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 decompressor for the corresponding format.
+@var{command} may include arguments. For example
+@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 @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 @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.
+@end enumerate
+
+@end table
+
+Numbers 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)
+@item R @tab ronnabyte  (10^27)       @tab | @tab Ri @tab robibyte  (2^90)
+@item Q @tab quettabyte (10^30)       @tab | @tab Qi @tab quebibyte (2^100)
+@end multitable
+
+
+@node Configuration
+@chapter The configuration file 'zutils.conf'
+@cindex zutils.conf
+
+@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{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{zutils.conf}.
+
+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
+Any line beginning with @samp{#} is a comment line.
+@item
+Each non-comment line defines the command to be used for the corresponding
+format, with the syntax:
+@example
+<format> = <compressor> [options]
+@end example
+where <format> is one of @samp{bz2}, @samp{gz}, @samp{lz}, @samp{xz}, or
+@samp{zst}.
+@end enumerate
+
+
+@node Zcat
+@chapter Zcat
+@cindex zcat
+
+@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 until one is found.
+@xref{search-order}. 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
+standard input must be of the same type; all uncompressed or all in the
+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 @command{zcat} is:
+
+@example
+zcat [@var{options}] [@var{files}]
+@end example
+
+@noindent
+Exit status is 0 if no errors occurred, 1 otherwise.
+
+@command{zcat} supports the following options:
+
+@table @code
+@item -A
+@itemx --show-all
+Equivalent to @option{-vET}.
+
+@item -b
+@itemx --number-nonblank
+Number all nonblank output lines, starting with 1. The line count is
+unlimited.
+
+@item -e
+Equivalent to @option{-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 compressed format given. Valid values for @var{format} are
+@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 checking
+their format, and the exact file name must be given. Other names are not
+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 given in the command line, but skip
+symbolic links 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 @option{-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. Repeating it increases the verbosity
+level. @xref{version}.
+
+@end table
+
+
+@node Zcmp
+@chapter Zcmp
+@cindex zcmp
+
+@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 @command{zcmp} is:
+
+@example
+zcmp [@var{options}] @var{file1} [@var{file2}]
+@end example
+
+@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 @command{zcmp} tries to compare @var{file1} with the corresponding
+uncompressed file (if @var{file1} is compressed), and then with the
+corresponding compressed files of the remaining formats until one is found.
+@xref{search-order}.
+
+@noindent
+An exit status of 0 means no differences were found, 1 means some
+differences were found, and 2 means trouble.
+
+@command{zcmp} supports the following options:
+
+@table @code
+@item -b
+@itemx --print-bytes
+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}
+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 --list
+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}
+Compare at most @var{count} input bytes.
+
+@item -O [@var{format1}][,@var{format2}]
+@itemx --force-format=[@var{format1}][,@var{format2}]
+Force the compressed formats given. If @var{format1} or @var{format2} is
+omitted, the corresponding format is automatically detected. Valid values
+for @var{format} are @samp{bz2}, @samp{gz}, @samp{lz}, @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 checking its format, and
+the exact file names of both @var{file1} and @var{file2} must be given.
+Other names are not tried.
+
+@item -q
+@itemx --quiet
+@itemx --silent
+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
+
+
+@node Zdiff
+@chapter Zdiff
+@cindex zdiff
+
+@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 @command{zdiff} is:
+
+@example
+zdiff [@var{options}] @var{file1} [@var{file2}]
+@end example
+
+@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 @command{zdiff} tries to compare @var{file1} with the corresponding
+uncompressed file (if @var{file1} is compressed), and then with the
+corresponding compressed files of the remaining formats until one is found.
+@xref{search-order}.
+
+@noindent
+An exit status of 0 means no differences were found, 1 means some
+differences were found, and 2 means trouble.
+
+@command{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.
+
+@item -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. Consider uppercase and lowercase letters equivalent.
+
+@item -O [@var{format1}][,@var{format2}]
+@itemx --force-format=[@var{format1}][,@var{format2}]
+Force the compressed formats given. If @var{format1} or @var{format2} is
+omitted, the corresponding format is automatically detected. Valid values
+for @var{format} are @samp{bz2}, @samp{gz}, @samp{lz}, @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 checking its format, and
+the exact file names of both @var{file1} and @var{file2} must be given.
+Other names are not 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 -v
+@itemx --verbose
+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
+Ignore all white space.
+
+@item -W @var{columns}
+@itemx --width=@var{columns}
+Output at most the specified number of print columns per line in side by
+side format.
+
+@item -y
+@itemx --side-by-side
+Use the side by side output format.
+
+@end table
+
+
+@node Zgrep
+@chapter Zgrep
+@cindex zgrep
+
+@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 until one is found. @xref{search-order}. 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,
+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 compressed format.
+
+If no files are specified, recursive searches examine the current working
+directory, and nonrecursive searches read standard input.
+
+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}]
+@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.
+
+@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
+@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
+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 @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
+@itemx --fixed-strings
+Interpret @var{pattern} as a set of newline-separated strings.
+
+@item -G
+@itemx --basic-regexp
+Interpret @var{pattern} as a basic regular expression (BRE). This is the
+default.
+
+@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. Stop reading each
+file on the first match.
+
+@item -L
+@itemx --files-without-match
+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.
+
+@item --label=@var{label}
+Display input actually coming from standard input as input coming from file
+@var{label}.
+
+@item --line-buffered
+Use line buffering on output. This may cause a performance penalty.
+
+@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 compressed format given. Valid values for @var{format} are
+@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 checking
+their format, and the exact file name must be given. Other names are not
+tried.
+
+@item -P
+@itemx --perl-regexp
+Interpret @var{pattern} as a Perl-compatible regular expression (PCRE).
+
+@item -q
+@itemx --quiet
+@itemx --silent
+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 given in the command line, but skip
+symbolic links 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 -T
+@itemx --initial-tab
+Make sure that the first character of actual line content lies on a tab
+stop, so that the alignment of tabs looks normal.
+
+@item -U
+@itemx --binary
+Use binary I/O on platforms affected by the bug known as "text mode I/O".
+(MS-DOS, MS-Windows, OS/2).
+
+@item -v
+@itemx --invert-match
+Select non-matching lines.
+
+@item --verbose
+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
+Match only whole words.
+
+@item -x
+@itemx --line-regexp
+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, @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
+
+
+@node Ztest
+@chapter Ztest
+@cindex ztest
+
+@command{ztest} checks 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 checked. 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 testing 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.
+
+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.
+
+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,,check 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 checked as reliably as files in
+the other formats can.
+@c We can only hope that xz is soon abandoned.
+
+The format for running @command{ztest} is:
+
+@example
+ztest [@var{options}] [@var{files}]
+@end example
+
+@noindent
+Exit status is 0 if all compressed files check 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.
+
+@command{ztest} supports the following options:
+
+@table @code
+@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
+checking their format, and any files in a format that the decompressor can't
+understand fail the test.
+
+@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 given in the command line, but skip
+symbolic links 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 check status for each file processed. Further -v's
+increase the verbosity level. @xref{version}.
+
+@end table
+
+
+@node Zupdate
+@chapter Zupdate
+@cindex zupdate
+
+@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 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 @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.
+
+Combining the options @option{--force} and @option{--keep}, as in
+@w{@samp{zupdate -f -k *.gz}}, checks 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{.gz}, @samp{.xz}, @samp{.zst}, or @samp{.Z}, which are
+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 @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
+@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 @command{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). 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 (invalid command-line options,
+compressor can't be run, or comparison fails).
+
+@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},
+@samp{.tgz}, @samp{.txz}, and @samp{.tzst} to @samp{tar.lz}.
+
+@item -f
+@itemx --force
+Don't skip a file for which a lzip-compressed version already exists.
+@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.
+
+@item -i
+@itemx --ignore-errors
+Ignore non-fatal errors. (See exit status above).
+
+@item -k
+@itemx --keep
+Keep (don't delete) the input file after comparing it with the lzip file.
+Use it when recompressing files from a read-only file system. (See option
+@option{--destdir} above).
+
+@item -l
+@itemx --lzip-verbose
+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 @option{-l} shows the progress of compression. Use it together with
+@option{-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 given in the command line, but skip
+symbolic links 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 @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 @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
+
+
+@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{@samp{zupdate --version}}.
+
+
+@node Concept index
+@unnumbered Concept index
+
+@printindex cp
+
+@bye